| Message ID | 20200131132829.10281-1-msuchanek@suse.de (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | a83836dbc53e96f13fec248ecc201d18e1e3111d |
| Headers | show |
| Series | [v2] powerpc: drmem: avoid NULL pointer dereference when drmem is unavailable | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (492a2f9203423062e77c862dd2256dc0e186690a) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | warning | total: 0 errors, 1 warnings, 0 checks, 35 lines checked |
| snowpatch_ozlabs/needsstable | success | Patch is tagged for stable |
Michal Suchanek <msuchanek@suse.de> writes: > From: Libor Pechacek <lpechacek@suse.cz> > > In guests without hotplugagble memory drmem structure is only zero > initialized. Trying to manipulate DLPAR parameters results in a crash. > [...] > > Fixes: 6c6ea53725b3 ("powerpc/mm: Separate ibm, dynamic-memory data from DT format") > Cc: Michal Suchanek <msuchanek@suse.cz> > Cc: stable@vger.kernel.org > Signed-off-by: Libor Pechacek <lpechacek@suse.cz> > Signed-off-by: Michal Suchanek <msuchanek@suse.de> > --- > v2: rename last_lmb -> limit, clarify error condition. Acked-by: Nathan Lynch <nathanl@linux.ibm.com> Thanks!
On Fri, 2020-01-31 at 13:28:29 UTC, Michal Suchanek wrote: > > From: Libor Pechacek <lpechacek@suse.cz> > > In guests without hotplugagble memory drmem structure is only zero > initialized. Trying to manipulate DLPAR parameters results in a crash. > > $ echo "memory add count 1" > /sys/kernel/dlpar > Oops: Kernel access of bad area, sig: 11 [#1] > LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries > Modules linked in: af_packet(E) rfkill(E) nvram(E) vmx_crypto(E) > gf128mul(E) e1000(E) virtio_balloon(E) rtc_generic(E) crct10dif_vpmsum(E) > btrfs(E) blake2b_generic(E) libcrc32c(E) xor(E) raid6_pq(E) virtio_rng(E) > virtio_blk(E) ohci_pci(E) ehci_pci(E) ohci_hcd(E) ehci_hcd(E) > crc32c_vpmsum(E) usbcore(E) virtio_pci(E) virtio_ring(E) virtio(E) sg(E) > dm_multipath(E) dm_mod(E) scsi_dh_rdac(E) scsi_dh_emc(E) scsi_dh_alua(E) > scsi_mod(E) > CPU: 1 PID: 4114 Comm: bash Kdump: loaded Tainted: G E 5.5.0-rc6-2-default #1 > NIP: c0000000000ff294 LR: c0000000000ff248 CTR: 0000000000000000 > REGS: c0000000fb9d3880 TRAP: 0300 Tainted: G E (5.5.0-rc6-2-default) > MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 28242428 XER: 20000000 > CFAR: c0000000009a6c10 DAR: 0000000000000010 DSISR: 40000000 IRQMASK: 0 > GPR00: c0000000000ff248 c0000000fb9d3b10 c000000001682e00 0000000000000033 > GPR04: c0000000ff30bf90 c0000000ff394800 0000000000005110 ffffffffffffffe8 > GPR08: 0000000000000000 0000000000000000 00000000fe1c0000 0000000000000000 > GPR12: 0000000000002200 c00000003fffee00 0000000000000000 000000011cbc37c0 > GPR16: 000000011cb27ed0 0000000000000000 000000011cb6dd10 0000000000000000 > GPR20: 000000011cb7db28 000001003ce035f0 000000011cbc7828 000000011cbc6c70 > GPR24: 000001003cf01210 0000000000000000 c0000000ffade4e0 c000000002d7216b > GPR28: 0000000000000001 c000000002d78560 0000000000000000 c0000000015458d0 > NIP [c0000000000ff294] dlpar_memory+0x6e4/0xd00 > LR [c0000000000ff248] dlpar_memory+0x698/0xd00 > Call Trace: > [c0000000fb9d3b10] [c0000000000ff248] dlpar_memory+0x698/0xd00 (unreliable) > [c0000000fb9d3ba0] [c0000000000f5990] handle_dlpar_errorlog+0xc0/0x190 > [c0000000fb9d3c10] [c0000000000f5c58] dlpar_store+0x198/0x4a0 > [c0000000fb9d3cd0] [c000000000c4cb00] kobj_attr_store+0x30/0x50 > [c0000000fb9d3cf0] [c0000000005a37b4] sysfs_kf_write+0x64/0x90 > [c0000000fb9d3d10] [c0000000005a2c90] kernfs_fop_write+0x1b0/0x290 > [c0000000fb9d3d60] [c0000000004a2bec] __vfs_write+0x3c/0x70 > [c0000000fb9d3d80] [c0000000004a6560] vfs_write+0xd0/0x260 > [c0000000fb9d3dd0] [c0000000004a69ac] ksys_write+0xdc/0x130 > [c0000000fb9d3e20] [c00000000000b478] system_call+0x5c/0x68 > Instruction dump: > ebc90000 1ce70018 38e7ffe8 7cfe3a14 7fbe3840 419dff14 fb610068 7fc9f378 > 39000000 4800000c 60000000 4195fef4 <81490010> 39290018 38c80001 7ea93840 > ---[ end trace cc2dd8152608c295 ]--- > > Taking closer look at the code, I can see that for_each_drmem_lmb is a > macro expanding into `for (lmb = &drmem_info->lmbs[0]; lmb <= > &drmem_info->lmbs[drmem_info->n_lmbs - 1]; lmb++)`. When drmem_info->lmbs > is NULL, the loop would iterate through the whole address range if it > weren't stopped by the NULL pointer dereference on the next line. > > This patch aligns for_each_drmem_lmb and for_each_drmem_lmb_in_range macro > behavior with the common C semantics, where the end marker does not belong > to the scanned range, and alters get_lmb_range() semantics. As a side > effect, the wraparound observed in the crash is prevented. > > Fixes: 6c6ea53725b3 ("powerpc/mm: Separate ibm, dynamic-memory data from DT format") > Cc: Michal Suchanek <msuchanek@suse.cz> > Cc: stable@vger.kernel.org > Signed-off-by: Libor Pechacek <lpechacek@suse.cz> > Signed-off-by: Michal Suchanek <msuchanek@suse.de> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/a83836dbc53e96f13fec248ecc201d18e1e3111d cheers
diff --git a/arch/powerpc/include/asm/drmem.h b/arch/powerpc/include/asm/drmem.h index 3d76e1c388c2..28c3d936fdf3 100644 --- a/arch/powerpc/include/asm/drmem.h +++ b/arch/powerpc/include/asm/drmem.h @@ -27,12 +27,12 @@ struct drmem_lmb_info { extern struct drmem_lmb_info *drmem_info; #define for_each_drmem_lmb_in_range(lmb, start, end) \ - for ((lmb) = (start); (lmb) <= (end); (lmb)++) + for ((lmb) = (start); (lmb) < (end); (lmb)++) #define for_each_drmem_lmb(lmb) \ for_each_drmem_lmb_in_range((lmb), \ &drmem_info->lmbs[0], \ - &drmem_info->lmbs[drmem_info->n_lmbs - 1]) + &drmem_info->lmbs[drmem_info->n_lmbs]) /* * The of_drconf_cell_v1 struct defines the layout of the LMB data diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c index c126b94d1943..a6b207dd1d7d 100644 --- a/arch/powerpc/platforms/pseries/hotplug-memory.c +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c @@ -223,7 +223,7 @@ static int get_lmb_range(u32 drc_index, int n_lmbs, struct drmem_lmb **end_lmb) { struct drmem_lmb *lmb, *start, *end; - struct drmem_lmb *last_lmb; + struct drmem_lmb *limit; start = NULL; for_each_drmem_lmb(lmb) { @@ -236,10 +236,10 @@ static int get_lmb_range(u32 drc_index, int n_lmbs, if (!start) return -EINVAL; - end = &start[n_lmbs - 1]; + end = &start[n_lmbs]; - last_lmb = &drmem_info->lmbs[drmem_info->n_lmbs - 1]; - if (end > last_lmb) + limit = &drmem_info->lmbs[drmem_info->n_lmbs]; + if (end > limit) return -EINVAL; *start_lmb = start;