| Message ID | 20220531041446.3334259-1-vaibhav@linux.ibm.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | [v3] of: check previous kernel's ima-kexec-buffer against memory bounds | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_kernel_qemu | fail | boot (pmac32_defconfig, mac99, qemu-system-ppc openbios-ppc, ppc-rootfs.cpio.gz, korg-5.5.0, fedo... failed at step Run qemu-mac99 with korg-5.5.0 build kernel. |
| snowpatch_ozlabs/github-powerpc_sparse | success | Successfully ran 4 jobs. |
| snowpatch_ozlabs/github-powerpc_clang | success | Successfully ran 7 jobs. |
On Tue, 31 May 2022 09:44:46 +0530, Vaibhav Jain wrote: > Presently ima_get_kexec_buffer() doesn't check if the previous kernel's > ima-kexec-buffer lies outside the addressable memory range. This can result > in a kernel panic if the new kernel is booted with 'mem=X' arg and the > ima-kexec-buffer was allocated beyond that range by the previous kernel. > The panic is usually of the form below: > > $ sudo kexec --initrd initrd vmlinux --append='mem=16G' > > <snip> > BUG: Unable to handle kernel data access on read at 0xc000c01fff7f0000 > Faulting instruction address: 0xc000000000837974 > Oops: Kernel access of bad area, sig: 11 [#1] > <snip> > NIP [c000000000837974] ima_restore_measurement_list+0x94/0x6c0 > LR [c00000000083b55c] ima_load_kexec_buffer+0xac/0x160 > Call Trace: > [c00000000371fa80] [c00000000083b55c] ima_load_kexec_buffer+0xac/0x160 > [c00000000371fb00] [c0000000020512c4] ima_init+0x80/0x108 > [c00000000371fb70] [c0000000020514dc] init_ima+0x4c/0x120 > [c00000000371fbf0] [c000000000012240] do_one_initcall+0x60/0x2c0 > [c00000000371fcc0] [c000000002004ad0] kernel_init_freeable+0x344/0x3ec > [c00000000371fda0] [c0000000000128a4] kernel_init+0x34/0x1b0 > [c00000000371fe10] [c00000000000ce64] ret_from_kernel_thread+0x5c/0x64 > Instruction dump: > f92100b8 f92100c0 90e10090 910100a0 4182050c 282a0017 3bc00000 40810330 > 7c0802a6 fb610198 7c9b2378 f80101d0 <a1240000> 2c090001 40820614 e9240010 > ---[ end trace 0000000000000000 ]--- > > Fix this issue by checking returned PFN range of previous kernel's > ima-kexec-buffer with page_is_ram() to ensure correct memory bounds. > > Fixes: 467d27824920 ("powerpc: ima: get the kexec buffer passed by the previous kernel") > Cc: Frank Rowand <frowand.list@gmail.com> > Cc: Prakhar Srivastava <prsriva@linux.microsoft.com> > Cc: Lakshmi Ramasubramanian <nramas@linux.microsoft.com> > Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com> > Cc: Rob Herring <robh@kernel.org> > Cc: Ritesh Harjani <ritesh.list@gmail.com> > Cc: Robin Murphy <robin.murphy@arm.com> > Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com> > --- > Changelog > ========== > v3: > * change the type for {start,end}_pfn to unsigned long [ Ritesh ] > * Switched to page_is_ram() from pfn_vaild() [ Rob ] > > v2: > * Instead of using memblock to determine the valid bounds use pfn_valid() to do > so since memblock may not be available late after the kernel init. [ Mpe ] > * Changed the patch prefix from 'powerpc' to 'of' [ Mpe ] > * Updated the 'Fixes' tag to point to correct commit that introduced this > function. [ Rob ] > * Fixed some whitespace/tab issues in the patch description [ Rob ] > * Added another check for checking ig 'tmp_size' for ima-kexec-buffer is > 0 > --- > drivers/of/kexec.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > Applied, thanks!
diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c index 8d374cc552be..91b04b04eec4 100644 --- a/drivers/of/kexec.c +++ b/drivers/of/kexec.c @@ -126,6 +126,7 @@ int ima_get_kexec_buffer(void **addr, size_t *size) { int ret, len; unsigned long tmp_addr; + unsigned long start_pfn, end_pfn; size_t tmp_size; const void *prop; @@ -140,6 +141,22 @@ int ima_get_kexec_buffer(void **addr, size_t *size) if (ret) return ret; + /* Do some sanity on the returned size for the ima-kexec buffer */ + if (!tmp_size) + return -ENOENT; + + /* + * Calculate the PFNs for the buffer and ensure + * they are with in addressable memory. + */ + start_pfn = PHYS_PFN(tmp_addr); + end_pfn = PHYS_PFN(tmp_addr + tmp_size - 1); + if (!page_is_ram(start_pfn) || !page_is_ram(end_pfn)) { + pr_warn("IMA buffer at 0x%lx, size = 0x%zx beyond memory\n", + tmp_addr, tmp_size); + return -EINVAL; + } + *addr = __va(tmp_addr); *size = tmp_size;
Presently ima_get_kexec_buffer() doesn't check if the previous kernel's ima-kexec-buffer lies outside the addressable memory range. This can result in a kernel panic if the new kernel is booted with 'mem=X' arg and the ima-kexec-buffer was allocated beyond that range by the previous kernel. The panic is usually of the form below: $ sudo kexec --initrd initrd vmlinux --append='mem=16G' <snip> BUG: Unable to handle kernel data access on read at 0xc000c01fff7f0000 Faulting instruction address: 0xc000000000837974 Oops: Kernel access of bad area, sig: 11 [#1] <snip> NIP [c000000000837974] ima_restore_measurement_list+0x94/0x6c0 LR [c00000000083b55c] ima_load_kexec_buffer+0xac/0x160 Call Trace: [c00000000371fa80] [c00000000083b55c] ima_load_kexec_buffer+0xac/0x160 [c00000000371fb00] [c0000000020512c4] ima_init+0x80/0x108 [c00000000371fb70] [c0000000020514dc] init_ima+0x4c/0x120 [c00000000371fbf0] [c000000000012240] do_one_initcall+0x60/0x2c0 [c00000000371fcc0] [c000000002004ad0] kernel_init_freeable+0x344/0x3ec [c00000000371fda0] [c0000000000128a4] kernel_init+0x34/0x1b0 [c00000000371fe10] [c00000000000ce64] ret_from_kernel_thread+0x5c/0x64 Instruction dump: f92100b8 f92100c0 90e10090 910100a0 4182050c 282a0017 3bc00000 40810330 7c0802a6 fb610198 7c9b2378 f80101d0 <a1240000> 2c090001 40820614 e9240010 ---[ end trace 0000000000000000 ]--- Fix this issue by checking returned PFN range of previous kernel's ima-kexec-buffer with page_is_ram() to ensure correct memory bounds. Fixes: 467d27824920 ("powerpc: ima: get the kexec buffer passed by the previous kernel") Cc: Frank Rowand <frowand.list@gmail.com> Cc: Prakhar Srivastava <prsriva@linux.microsoft.com> Cc: Lakshmi Ramasubramanian <nramas@linux.microsoft.com> Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com> Cc: Rob Herring <robh@kernel.org> Cc: Ritesh Harjani <ritesh.list@gmail.com> Cc: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com> --- Changelog ========== v3: * change the type for {start,end}_pfn to unsigned long [ Ritesh ] * Switched to page_is_ram() from pfn_vaild() [ Rob ] v2: * Instead of using memblock to determine the valid bounds use pfn_valid() to do so since memblock may not be available late after the kernel init. [ Mpe ] * Changed the patch prefix from 'powerpc' to 'of' [ Mpe ] * Updated the 'Fixes' tag to point to correct commit that introduced this function. [ Rob ] * Fixed some whitespace/tab issues in the patch description [ Rob ] * Added another check for checking ig 'tmp_size' for ima-kexec-buffer is > 0 --- drivers/of/kexec.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)