| Message ID | 20240527183007.1595037-1-cascardo@igalia.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 3f0c44c8c21cfa3bb6b756b939491b7a60932cd1 |
| Headers | show |
| Series | codetag: avoid race at alloc_slab_obj_exts | expand |
On 5/27/24 8:30 PM, Thadeu Lima de Souza Cascardo wrote: > When CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled, the following warning may > be noticed: > > [ 48.299584] ------------[ cut here ]------------ > [ 48.300092] alloc_tag was not set > [ 48.300528] WARNING: CPU: 2 PID: 1361 at include/linux/alloc_tag.h:130 alloc_tagging_slab_free_hook+0x84/0xc7 > [ 48.301305] Modules linked in: > [ 48.301553] CPU: 2 PID: 1361 Comm: systemd-udevd Not tainted 6.10.0-rc1-00003-gac8755535862 #176 > [ 48.302196] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 > [ 48.302752] RIP: 0010:alloc_tagging_slab_free_hook+0x84/0xc7 > [ 48.303169] Code: 8d 1c c4 48 85 db 74 4d 48 83 3b 00 75 1e 80 3d 65 02 86 04 00 75 15 48 c7 c7 11 48 1d 85 c6 05 55 02 86 04 01 e8 64 44 a5 ff <0f> 0b 48 8b 03 48 85 c0 74 21 48 83 f8 01 74 14 48 8b 50 20 48 f7 > [ 48.304411] RSP: 0018:ffff8880111b7d40 EFLAGS: 00010282 > [ 48.304916] RAX: 0000000000000000 RBX: ffff88800fcc9008 RCX: 0000000000000000 > [ 48.305455] RDX: 0000000080000000 RSI: ffff888014060000 RDI: ffffed1002236f97 > [ 48.305979] RBP: 0000000000001100 R08: fffffbfff0aa73a1 R09: 0000000000000000 > [ 48.306473] R10: ffffffff814515e5 R11: 0000000000000003 R12: ffff88800fcc9000 > [ 48.306943] R13: ffff88800b2e5cc0 R14: ffff8880111b7d90 R15: 0000000000000000 > [ 48.307529] FS: 00007faf5d1908c0(0000) GS:ffff88806cf00000(0000) knlGS:0000000000000000 > [ 48.308223] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 48.308710] CR2: 000058fb220c9118 CR3: 00000000110cc000 CR4: 0000000000750ef0 > [ 48.309274] PKRU: 55555554 > [ 48.309804] Call Trace: > [ 48.310029] <TASK> > [ 48.310290] ? show_regs+0x84/0x8d > [ 48.310722] ? alloc_tagging_slab_free_hook+0x84/0xc7 > [ 48.311298] ? __warn+0x13b/0x2ff > [ 48.311580] ? alloc_tagging_slab_free_hook+0x84/0xc7 > [ 48.311987] ? report_bug+0x2ce/0x3ab > [ 48.312292] ? handle_bug+0x8c/0x107 > [ 48.312563] ? exc_invalid_op+0x34/0x6f > [ 48.312842] ? asm_exc_invalid_op+0x1a/0x20 > [ 48.313173] ? this_cpu_in_panic+0x1c/0x72 > [ 48.313503] ? alloc_tagging_slab_free_hook+0x84/0xc7 > [ 48.313880] ? putname+0x143/0x14e > [ 48.314152] kmem_cache_free+0xe9/0x214 > [ 48.314454] putname+0x143/0x14e > [ 48.314712] do_unlinkat+0x413/0x45e > [ 48.315001] ? __pfx_do_unlinkat+0x10/0x10 > [ 48.315388] ? __check_object_size+0x4d7/0x525 > [ 48.315744] ? __sanitizer_cov_trace_pc+0x20/0x4a > [ 48.316167] ? __sanitizer_cov_trace_pc+0x20/0x4a > [ 48.316757] ? getname_flags+0x4ed/0x500 > [ 48.317261] __x64_sys_unlink+0x42/0x4a > [ 48.317741] do_syscall_64+0xe2/0x149 > [ 48.318171] entry_SYSCALL_64_after_hwframe+0x76/0x7e > [ 48.318602] RIP: 0033:0x7faf5d8850ab > [ 48.318891] Code: fd ff ff e8 27 dd 01 00 0f 1f 80 00 00 00 00 f3 0f 1e fa b8 5f 00 00 00 0f 05 c3 0f 1f 40 00 f3 0f 1e fa b8 57 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 8b 15 41 2d 0e 00 f7 d8 > [ 48.320649] RSP: 002b:00007ffc44982b38 EFLAGS: 00000246 ORIG_RAX: 0000000000000057 > [ 48.321182] RAX: ffffffffffffffda RBX: 00005ba344a44680 RCX: 00007faf5d8850ab > [ 48.321667] RDX: 0000000000000000 RSI: 00005ba344a44430 RDI: 00007ffc44982b40 > [ 48.322139] RBP: 00007ffc44982c00 R08: 0000000000000000 R09: 0000000000000007 > [ 48.322598] R10: 00005ba344a44430 R11: 0000000000000246 R12: 0000000000000000 > [ 48.323071] R13: 00007ffc44982b40 R14: 0000000000000000 R15: 0000000000000000 > [ 48.323596] </TASK> > > This is due to a race when two objects are allocated from the same slab, > which did not have an obj_exts allocated for. > > In such a case, the two threads will notice the NULL obj_exts and after one > assigns slab->obj_exts, the second one will happily do the exchange if it > reads this new assigned value. > > In order to avoid that, verify that the read obj_exts does not point to an > allocated obj_exts before doing the exchange. > > Fixes: 09c46563ff6d ("codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mark failed slab_ext allocations") > Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com> > Cc: Suren Baghdasaryan <surenb@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Thanks! > --- > mm/slub.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 0809760cf789..1373ac365a46 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -1952,7 +1952,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, > #ifdef CONFIG_MEMCG > new_exts |= MEMCG_DATA_OBJEXTS; > #endif > - old_exts = slab->obj_exts; > + old_exts = READ_ONCE(slab->obj_exts); > handle_failed_objexts_alloc(old_exts, vec, objects); > if (new_slab) { > /* > @@ -1961,7 +1961,8 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, > * be simply assigned. > */ > slab->obj_exts = new_exts; > - } else if (cmpxchg(&slab->obj_exts, old_exts, new_exts) != old_exts) { > + } else if ((old_exts & ~OBJEXTS_FLAGS_MASK) || > + cmpxchg(&slab->obj_exts, old_exts, new_exts) != old_exts) { > /* > * If the slab is already in use, somebody can allocate and > * assign slabobj_exts in parallel. In this case the existing
diff --git a/mm/slub.c b/mm/slub.c index 0809760cf789..1373ac365a46 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1952,7 +1952,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, #ifdef CONFIG_MEMCG new_exts |= MEMCG_DATA_OBJEXTS; #endif - old_exts = slab->obj_exts; + old_exts = READ_ONCE(slab->obj_exts); handle_failed_objexts_alloc(old_exts, vec, objects); if (new_slab) { /* @@ -1961,7 +1961,8 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, * be simply assigned. */ slab->obj_exts = new_exts; - } else if (cmpxchg(&slab->obj_exts, old_exts, new_exts) != old_exts) { + } else if ((old_exts & ~OBJEXTS_FLAGS_MASK) || + cmpxchg(&slab->obj_exts, old_exts, new_exts) != old_exts) { /* * If the slab is already in use, somebody can allocate and * assign slabobj_exts in parallel. In this case the existing
When CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled, the following warning may be noticed: [ 48.299584] ------------[ cut here ]------------ [ 48.300092] alloc_tag was not set [ 48.300528] WARNING: CPU: 2 PID: 1361 at include/linux/alloc_tag.h:130 alloc_tagging_slab_free_hook+0x84/0xc7 [ 48.301305] Modules linked in: [ 48.301553] CPU: 2 PID: 1361 Comm: systemd-udevd Not tainted 6.10.0-rc1-00003-gac8755535862 #176 [ 48.302196] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 [ 48.302752] RIP: 0010:alloc_tagging_slab_free_hook+0x84/0xc7 [ 48.303169] Code: 8d 1c c4 48 85 db 74 4d 48 83 3b 00 75 1e 80 3d 65 02 86 04 00 75 15 48 c7 c7 11 48 1d 85 c6 05 55 02 86 04 01 e8 64 44 a5 ff <0f> 0b 48 8b 03 48 85 c0 74 21 48 83 f8 01 74 14 48 8b 50 20 48 f7 [ 48.304411] RSP: 0018:ffff8880111b7d40 EFLAGS: 00010282 [ 48.304916] RAX: 0000000000000000 RBX: ffff88800fcc9008 RCX: 0000000000000000 [ 48.305455] RDX: 0000000080000000 RSI: ffff888014060000 RDI: ffffed1002236f97 [ 48.305979] RBP: 0000000000001100 R08: fffffbfff0aa73a1 R09: 0000000000000000 [ 48.306473] R10: ffffffff814515e5 R11: 0000000000000003 R12: ffff88800fcc9000 [ 48.306943] R13: ffff88800b2e5cc0 R14: ffff8880111b7d90 R15: 0000000000000000 [ 48.307529] FS: 00007faf5d1908c0(0000) GS:ffff88806cf00000(0000) knlGS:0000000000000000 [ 48.308223] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 48.308710] CR2: 000058fb220c9118 CR3: 00000000110cc000 CR4: 0000000000750ef0 [ 48.309274] PKRU: 55555554 [ 48.309804] Call Trace: [ 48.310029] <TASK> [ 48.310290] ? show_regs+0x84/0x8d [ 48.310722] ? alloc_tagging_slab_free_hook+0x84/0xc7 [ 48.311298] ? __warn+0x13b/0x2ff [ 48.311580] ? alloc_tagging_slab_free_hook+0x84/0xc7 [ 48.311987] ? report_bug+0x2ce/0x3ab [ 48.312292] ? handle_bug+0x8c/0x107 [ 48.312563] ? exc_invalid_op+0x34/0x6f [ 48.312842] ? asm_exc_invalid_op+0x1a/0x20 [ 48.313173] ? this_cpu_in_panic+0x1c/0x72 [ 48.313503] ? alloc_tagging_slab_free_hook+0x84/0xc7 [ 48.313880] ? putname+0x143/0x14e [ 48.314152] kmem_cache_free+0xe9/0x214 [ 48.314454] putname+0x143/0x14e [ 48.314712] do_unlinkat+0x413/0x45e [ 48.315001] ? __pfx_do_unlinkat+0x10/0x10 [ 48.315388] ? __check_object_size+0x4d7/0x525 [ 48.315744] ? __sanitizer_cov_trace_pc+0x20/0x4a [ 48.316167] ? __sanitizer_cov_trace_pc+0x20/0x4a [ 48.316757] ? getname_flags+0x4ed/0x500 [ 48.317261] __x64_sys_unlink+0x42/0x4a [ 48.317741] do_syscall_64+0xe2/0x149 [ 48.318171] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 48.318602] RIP: 0033:0x7faf5d8850ab [ 48.318891] Code: fd ff ff e8 27 dd 01 00 0f 1f 80 00 00 00 00 f3 0f 1e fa b8 5f 00 00 00 0f 05 c3 0f 1f 40 00 f3 0f 1e fa b8 57 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 8b 15 41 2d 0e 00 f7 d8 [ 48.320649] RSP: 002b:00007ffc44982b38 EFLAGS: 00000246 ORIG_RAX: 0000000000000057 [ 48.321182] RAX: ffffffffffffffda RBX: 00005ba344a44680 RCX: 00007faf5d8850ab [ 48.321667] RDX: 0000000000000000 RSI: 00005ba344a44430 RDI: 00007ffc44982b40 [ 48.322139] RBP: 00007ffc44982c00 R08: 0000000000000000 R09: 0000000000000007 [ 48.322598] R10: 00005ba344a44430 R11: 0000000000000246 R12: 0000000000000000 [ 48.323071] R13: 00007ffc44982b40 R14: 0000000000000000 R15: 0000000000000000 [ 48.323596] </TASK> This is due to a race when two objects are allocated from the same slab, which did not have an obj_exts allocated for. In such a case, the two threads will notice the NULL obj_exts and after one assigns slab->obj_exts, the second one will happily do the exchange if it reads this new assigned value. In order to avoid that, verify that the read obj_exts does not point to an allocated obj_exts before doing the exchange. Fixes: 09c46563ff6d ("codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mark failed slab_ext allocations") Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com> Cc: Suren Baghdasaryan <surenb@google.com> --- mm/slub.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)