| Message ID | 20230130014707.541110-1-mpe@ellerman.id.au (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 7294194b47e994753a86eee8cf1c61f3f36458a3 |
| Headers | show |
| Series | powerpc/kexec_file: Fix division by zero in extra size estimation | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_ppctests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_selftests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_kernel_qemu | success | Successfully ran 24 jobs. |
| snowpatch_ozlabs/github-powerpc_sparse | success | Successfully ran 4 jobs. |
| snowpatch_ozlabs/github-powerpc_clang | success | Successfully ran 6 jobs. |
Hello Michael, On 30/01/23 07:17, Michael Ellerman wrote: > In kexec_extra_fdt_size_ppc64() there's logic to estimate how much > extra space will be needed in the device tree for some memory related > properties. > > That logic uses the size of RAM divided by drmem_lmb_size() to do the > estimation. However drmem_lmb_size() can be zero if the machine has no > hotpluggable memory configured, which is the case when booting with qemu > and no maxmem=x parameter is passed (the default). > > The division by zero is reported by UBSAN, and can also lead to an > overflow and a warning from kvmalloc, and kdump kernel loading fails: > > WARNING: CPU: 0 PID: 133 at mm/util.c:596 kvmalloc_node+0x15c/0x160 > Modules linked in: > CPU: 0 PID: 133 Comm: kexec Not tainted 6.2.0-rc5-03455-g07358bd97810 #223 > Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1200 0xf000005 of:SLOF,git-dd0dca pSeries > NIP: c00000000041ff4c LR: c00000000041fe58 CTR: 0000000000000000 > REGS: c0000000096ef750 TRAP: 0700 Not tainted (6.2.0-rc5-03455-g07358bd97810) > MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24248242 XER: 2004011e > CFAR: c00000000041fed0 IRQMASK: 0 > ... > NIP kvmalloc_node+0x15c/0x160 > LR kvmalloc_node+0x68/0x160 > Call Trace: > kvmalloc_node+0x68/0x160 (unreliable) > of_kexec_alloc_and_setup_fdt+0xb8/0x7d0 > elf64_load+0x25c/0x4a0 > kexec_image_load_default+0x58/0x80 > sys_kexec_file_load+0x5c0/0x920 > system_call_exception+0x128/0x330 > system_call_vectored_common+0x15c/0x2ec > > To fix it, skip the calculation if drmem_lmb_size() is zero. > > Fixes: 2377c92e37fe ("powerpc/kexec_file: fix FDT size estimation for kdump kernel") > Cc: stable@vger.kernel.org # v5.12+ > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> > --- > arch/powerpc/kexec/file_load_64.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c > index af8854f9eae3..3caee570e79b 100644 > --- a/arch/powerpc/kexec/file_load_64.c > +++ b/arch/powerpc/kexec/file_load_64.c > @@ -989,10 +989,12 @@ unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image) > * linux,drconf-usable-memory properties. Get an approximate on the > * number of usable memory entries and use for FDT size estimation. > */ > - usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) + > - (2 * (resource_size(&crashk_res) / drmem_lmb_size()))); > - > - extra_size = (unsigned int)(usm_entries * sizeof(u64)); > + if (drmem_lmb_size()) { > + usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) + > + (2 * (resource_size(&crashk_res) / drmem_lmb_size()))); > + extra_size = (unsigned int)(usm_entries * sizeof(u64)); > + } else > + extra_size = 0; > > /* > * Get the number of CPU nodes in the current DT. This allows to I failed to replicate this issue. Qemu command used: $ qemu-system-ppc64 -enable-kvm -smp 4,cores=2 -drive file=my-image.qcow2 -nographic -m 2G lsmem (inside guest): RANGE SIZE STATE REMOVABLE BLOCK 0x0000000000000000-0x000000007fffffff 2G online yes 0-127 Memory block size: 16M Total online memory: 2G Total offline memory: 0B Not sure what I am missing, but changes looks good to me. Thanks, Sourabh Jain
Sourabh Jain <sourabhjain@linux.ibm.com> writes: > On 30/01/23 07:17, Michael Ellerman wrote: >> In kexec_extra_fdt_size_ppc64() there's logic to estimate how much >> extra space will be needed in the device tree for some memory related >> properties. >> >> That logic uses the size of RAM divided by drmem_lmb_size() to do the >> estimation. However drmem_lmb_size() can be zero if the machine has no >> hotpluggable memory configured, which is the case when booting with qemu >> and no maxmem=x parameter is passed (the default). >> >> The division by zero is reported by UBSAN, and can also lead to an >> overflow and a warning from kvmalloc, and kdump kernel loading fails: >> >> WARNING: CPU: 0 PID: 133 at mm/util.c:596 kvmalloc_node+0x15c/0x160 >> Modules linked in: >> CPU: 0 PID: 133 Comm: kexec Not tainted 6.2.0-rc5-03455-g07358bd97810 #223 >> Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1200 0xf000005 of:SLOF,git-dd0dca pSeries >> NIP: c00000000041ff4c LR: c00000000041fe58 CTR: 0000000000000000 >> REGS: c0000000096ef750 TRAP: 0700 Not tainted (6.2.0-rc5-03455-g07358bd97810) >> MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24248242 XER: 2004011e >> CFAR: c00000000041fed0 IRQMASK: 0 >> ... >> NIP kvmalloc_node+0x15c/0x160 >> LR kvmalloc_node+0x68/0x160 >> Call Trace: >> kvmalloc_node+0x68/0x160 (unreliable) >> of_kexec_alloc_and_setup_fdt+0xb8/0x7d0 >> elf64_load+0x25c/0x4a0 >> kexec_image_load_default+0x58/0x80 >> sys_kexec_file_load+0x5c0/0x920 >> system_call_exception+0x128/0x330 >> system_call_vectored_common+0x15c/0x2ec >> >> To fix it, skip the calculation if drmem_lmb_size() is zero. >> >> Fixes: 2377c92e37fe ("powerpc/kexec_file: fix FDT size estimation for kdump kernel") >> Cc: stable@vger.kernel.org # v5.12+ >> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> >> --- >> arch/powerpc/kexec/file_load_64.c | 10 ++++++---- >> 1 file changed, 6 insertions(+), 4 deletions(-) >> >> diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c >> index af8854f9eae3..3caee570e79b 100644 >> --- a/arch/powerpc/kexec/file_load_64.c >> +++ b/arch/powerpc/kexec/file_load_64.c >> @@ -989,10 +989,12 @@ unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image) >> * linux,drconf-usable-memory properties. Get an approximate on the >> * number of usable memory entries and use for FDT size estimation. >> */ >> - usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) + >> - (2 * (resource_size(&crashk_res) / drmem_lmb_size()))); >> - >> - extra_size = (unsigned int)(usm_entries * sizeof(u64)); >> + if (drmem_lmb_size()) { >> + usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) + >> + (2 * (resource_size(&crashk_res) / drmem_lmb_size()))); >> + extra_size = (unsigned int)(usm_entries * sizeof(u64)); >> + } else >> + extra_size = 0; >> >> /* >> * Get the number of CPU nodes in the current DT. This allows to > > I failed to replicate this issue. > > Qemu command used: > $ qemu-system-ppc64 -enable-kvm -smp 4,cores=2 -drive > file=my-image.qcow2 -nographic -m 2G > > > lsmem (inside guest): > RANGE SIZE STATE REMOVABLE BLOCK > 0x0000000000000000-0x000000007fffffff 2G online yes 0-127 > > Memory block size: 16M > Total online memory: 2G > Total offline memory: 0B > > Not sure what I am missing, but changes looks good to me. Hmm, interesting. Do you have /proc/device-tree/ibm,dynamic-reconfiguration-memory in the VM? What version of qemu are you using? I think I tested with 6.2 and 7.1. cheers
On 01/02/23 07:25, Michael Ellerman wrote: > Sourabh Jain <sourabhjain@linux.ibm.com> writes: >> On 30/01/23 07:17, Michael Ellerman wrote: >>> In kexec_extra_fdt_size_ppc64() there's logic to estimate how much >>> extra space will be needed in the device tree for some memory related >>> properties. >>> >>> That logic uses the size of RAM divided by drmem_lmb_size() to do the >>> estimation. However drmem_lmb_size() can be zero if the machine has no >>> hotpluggable memory configured, which is the case when booting with qemu >>> and no maxmem=x parameter is passed (the default). >>> >>> The division by zero is reported by UBSAN, and can also lead to an >>> overflow and a warning from kvmalloc, and kdump kernel loading fails: >>> >>> WARNING: CPU: 0 PID: 133 at mm/util.c:596 kvmalloc_node+0x15c/0x160 >>> Modules linked in: >>> CPU: 0 PID: 133 Comm: kexec Not tainted 6.2.0-rc5-03455-g07358bd97810 #223 >>> Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1200 0xf000005 of:SLOF,git-dd0dca pSeries >>> NIP: c00000000041ff4c LR: c00000000041fe58 CTR: 0000000000000000 >>> REGS: c0000000096ef750 TRAP: 0700 Not tainted (6.2.0-rc5-03455-g07358bd97810) >>> MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24248242 XER: 2004011e >>> CFAR: c00000000041fed0 IRQMASK: 0 >>> ... >>> NIP kvmalloc_node+0x15c/0x160 >>> LR kvmalloc_node+0x68/0x160 >>> Call Trace: >>> kvmalloc_node+0x68/0x160 (unreliable) >>> of_kexec_alloc_and_setup_fdt+0xb8/0x7d0 >>> elf64_load+0x25c/0x4a0 >>> kexec_image_load_default+0x58/0x80 >>> sys_kexec_file_load+0x5c0/0x920 >>> system_call_exception+0x128/0x330 >>> system_call_vectored_common+0x15c/0x2ec >>> >>> To fix it, skip the calculation if drmem_lmb_size() is zero. >>> >>> Fixes: 2377c92e37fe ("powerpc/kexec_file: fix FDT size estimation for kdump kernel") >>> Cc: stable@vger.kernel.org # v5.12+ >>> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> >>> --- >>> arch/powerpc/kexec/file_load_64.c | 10 ++++++---- >>> 1 file changed, 6 insertions(+), 4 deletions(-) >>> >>> diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c >>> index af8854f9eae3..3caee570e79b 100644 >>> --- a/arch/powerpc/kexec/file_load_64.c >>> +++ b/arch/powerpc/kexec/file_load_64.c >>> @@ -989,10 +989,12 @@ unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image) >>> * linux,drconf-usable-memory properties. Get an approximate on the >>> * number of usable memory entries and use for FDT size estimation. >>> */ >>> - usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) + >>> - (2 * (resource_size(&crashk_res) / drmem_lmb_size()))); >>> - >>> - extra_size = (unsigned int)(usm_entries * sizeof(u64)); >>> + if (drmem_lmb_size()) { >>> + usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) + >>> + (2 * (resource_size(&crashk_res) / drmem_lmb_size()))); >>> + extra_size = (unsigned int)(usm_entries * sizeof(u64)); >>> + } else >>> + extra_size = 0; >>> >>> /* >>> * Get the number of CPU nodes in the current DT. This allows to >> I failed to replicate this issue. >> >> Qemu command used: >> $ qemu-system-ppc64 -enable-kvm -smp 4,cores=2 -drive >> file=my-image.qcow2 -nographic -m 2G >> >> >> lsmem (inside guest): >> RANGE SIZE STATE REMOVABLE BLOCK >> 0x0000000000000000-0x000000007fffffff 2G online yes 0-127 >> >> Memory block size: 16M >> Total online memory: 2G >> Total offline memory: 0B >> >> Not sure what I am missing, but changes looks good to me. > Hmm, interesting. > > Do you have /proc/device-tree/ibm,dynamic-reconfiguration-memory in the VM? No I don't. But if I add maxmem=x to qemu command line then ibm,dynamic-reconfiguration DT node comes up. > What version of qemu are you using? I think I tested with 6.2 and 7.1. QEMU emulator version 7.2.50 (v7.2.0-904-g13356edb87) I tried with QEMU emulator version 7.1.0 (v7.1.0), but not able to replicate it. - Sourabh
Thanks for the fix, Michael. On 30/01/23 7:17 am, Michael Ellerman wrote: > In kexec_extra_fdt_size_ppc64() there's logic to estimate how much > extra space will be needed in the device tree for some memory related > properties. > > That logic uses the size of RAM divided by drmem_lmb_size() to do the > estimation. However drmem_lmb_size() can be zero if the machine has no > hotpluggable memory configured, which is the case when booting with qemu > and no maxmem=x parameter is passed (the default). > > The division by zero is reported by UBSAN, and can also lead to an > overflow and a warning from kvmalloc, and kdump kernel loading fails: > > WARNING: CPU: 0 PID: 133 at mm/util.c:596 kvmalloc_node+0x15c/0x160 > Modules linked in: > CPU: 0 PID: 133 Comm: kexec Not tainted 6.2.0-rc5-03455-g07358bd97810 #223 > Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1200 0xf000005 of:SLOF,git-dd0dca pSeries > NIP: c00000000041ff4c LR: c00000000041fe58 CTR: 0000000000000000 > REGS: c0000000096ef750 TRAP: 0700 Not tainted (6.2.0-rc5-03455-g07358bd97810) > MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24248242 XER: 2004011e > CFAR: c00000000041fed0 IRQMASK: 0 > ... > NIP kvmalloc_node+0x15c/0x160 > LR kvmalloc_node+0x68/0x160 > Call Trace: > kvmalloc_node+0x68/0x160 (unreliable) > of_kexec_alloc_and_setup_fdt+0xb8/0x7d0 > elf64_load+0x25c/0x4a0 > kexec_image_load_default+0x58/0x80 > sys_kexec_file_load+0x5c0/0x920 > system_call_exception+0x128/0x330 > system_call_vectored_common+0x15c/0x2ec > > To fix it, skip the calculation if drmem_lmb_size() is zero. > > Fixes: 2377c92e37fe ("powerpc/kexec_file: fix FDT size estimation for kdump kernel") > Cc: stable@vger.kernel.org # v5.12+ > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Acked-by: Hari Bathini <hbathini@in.ibm.com> > --- > arch/powerpc/kexec/file_load_64.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c > index af8854f9eae3..3caee570e79b 100644 > --- a/arch/powerpc/kexec/file_load_64.c > +++ b/arch/powerpc/kexec/file_load_64.c > @@ -989,10 +989,12 @@ unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image) > * linux,drconf-usable-memory properties. Get an approximate on the > * number of usable memory entries and use for FDT size estimation. > */ > - usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) + > - (2 * (resource_size(&crashk_res) / drmem_lmb_size()))); > - > - extra_size = (unsigned int)(usm_entries * sizeof(u64)); > + if (drmem_lmb_size()) { > + usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) + > + (2 * (resource_size(&crashk_res) / drmem_lmb_size()))); > + extra_size = (unsigned int)(usm_entries * sizeof(u64)); > + } else > + extra_size = 0; > > /* > * Get the number of CPU nodes in the current DT. This allows to
On Mon, 30 Jan 2023 12:47:07 +1100, Michael Ellerman wrote: > In kexec_extra_fdt_size_ppc64() there's logic to estimate how much > extra space will be needed in the device tree for some memory related > properties. > > That logic uses the size of RAM divided by drmem_lmb_size() to do the > estimation. However drmem_lmb_size() can be zero if the machine has no > hotpluggable memory configured, which is the case when booting with qemu > and no maxmem=x parameter is passed (the default). > > [...] Applied to powerpc/fixes. [1/1] powerpc/kexec_file: Fix division by zero in extra size estimation https://git.kernel.org/powerpc/c/7294194b47e994753a86eee8cf1c61f3f36458a3 cheers
diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c index af8854f9eae3..3caee570e79b 100644 --- a/arch/powerpc/kexec/file_load_64.c +++ b/arch/powerpc/kexec/file_load_64.c @@ -989,10 +989,12 @@ unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image) * linux,drconf-usable-memory properties. Get an approximate on the * number of usable memory entries and use for FDT size estimation. */ - usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) + - (2 * (resource_size(&crashk_res) / drmem_lmb_size()))); - - extra_size = (unsigned int)(usm_entries * sizeof(u64)); + if (drmem_lmb_size()) { + usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) + + (2 * (resource_size(&crashk_res) / drmem_lmb_size()))); + extra_size = (unsigned int)(usm_entries * sizeof(u64)); + } else + extra_size = 0; /* * Get the number of CPU nodes in the current DT. This allows to
In kexec_extra_fdt_size_ppc64() there's logic to estimate how much extra space will be needed in the device tree for some memory related properties. That logic uses the size of RAM divided by drmem_lmb_size() to do the estimation. However drmem_lmb_size() can be zero if the machine has no hotpluggable memory configured, which is the case when booting with qemu and no maxmem=x parameter is passed (the default). The division by zero is reported by UBSAN, and can also lead to an overflow and a warning from kvmalloc, and kdump kernel loading fails: WARNING: CPU: 0 PID: 133 at mm/util.c:596 kvmalloc_node+0x15c/0x160 Modules linked in: CPU: 0 PID: 133 Comm: kexec Not tainted 6.2.0-rc5-03455-g07358bd97810 #223 Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1200 0xf000005 of:SLOF,git-dd0dca pSeries NIP: c00000000041ff4c LR: c00000000041fe58 CTR: 0000000000000000 REGS: c0000000096ef750 TRAP: 0700 Not tainted (6.2.0-rc5-03455-g07358bd97810) MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24248242 XER: 2004011e CFAR: c00000000041fed0 IRQMASK: 0 ... NIP kvmalloc_node+0x15c/0x160 LR kvmalloc_node+0x68/0x160 Call Trace: kvmalloc_node+0x68/0x160 (unreliable) of_kexec_alloc_and_setup_fdt+0xb8/0x7d0 elf64_load+0x25c/0x4a0 kexec_image_load_default+0x58/0x80 sys_kexec_file_load+0x5c0/0x920 system_call_exception+0x128/0x330 system_call_vectored_common+0x15c/0x2ec To fix it, skip the calculation if drmem_lmb_size() is zero. Fixes: 2377c92e37fe ("powerpc/kexec_file: fix FDT size estimation for kdump kernel") Cc: stable@vger.kernel.org # v5.12+ Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> --- arch/powerpc/kexec/file_load_64.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)