CVE-2023-53621

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> memcontrol: ensure memcg acquired by id is properly set up<br /> <br /> In the eviction recency check, we attempt to retrieve the memcg to which<br /> the folio belonged when it was evicted, by the memcg id stored in the<br /> shadow entry. However, there is a chance that the retrieved memcg is not<br /> the original memcg that has been killed, but a new one which happens to<br /> have the same id.<br /> <br /> This is a somewhat unfortunate, but acceptable and rare inaccuracy in the<br /> heuristics. However, if we retrieve this new memcg between its allocation<br /> and when it is properly attached to the memcg hierarchy, we could run into<br /> the following NULL pointer exception during the memcg hierarchy traversal<br /> done in mem_cgroup_get_nr_swap_pages():<br /> <br /> [ 155757.793456] BUG: kernel NULL pointer dereference, address: 00000000000000c0<br /> [ 155757.807568] #PF: supervisor read access in kernel mode<br /> [ 155757.818024] #PF: error_code(0x0000) - not-present page<br /> [ 155757.828482] PGD 401f77067 P4D 401f77067 PUD 401f76067 PMD 0<br /> [ 155757.839985] Oops: 0000 [#1] SMP<br /> [ 155757.887870] RIP: 0010:mem_cgroup_get_nr_swap_pages+0x3d/0xb0<br /> [ 155757.899377] Code: 29 19 4a 02 48 39 f9 74 63 48 8b 97 c0 00 00 00 48 8b b7 58 02 00 00 48 2b b7 c0 01 00 00 48 39 f0 48 0f 4d c6 48 39 d1 74 42 8b b2 c0 00 00 00 48 8b ba 58 02 00 00 48 2b ba c0 01 00 00 48<br /> [ 155757.937125] RSP: 0018:ffffc9002ecdfbc8 EFLAGS: 00010286<br /> [ 155757.947755] RAX: 00000000003a3b1c RBX: 000007ffffffffff RCX: ffff888280183000<br /> [ 155757.962202] RDX: 0000000000000000 RSI: 0007ffffffffffff RDI: ffff888bbc2d1000<br /> [ 155757.976648] RBP: 0000000000000001 R08: 000000000000000b R09: ffff888ad9cedba0<br /> [ 155757.991094] R10: ffffea0039c07900 R11: 0000000000000010 R12: ffff888b23a7b000<br /> [ 155758.005540] R13: 0000000000000000 R14: ffff888bbc2d1000 R15: 000007ffffc71354<br /> [ 155758.019991] FS: 00007f6234c68640(0000) GS:ffff88903f9c0000(0000) knlGS:0000000000000000<br /> [ 155758.036356] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br /> [ 155758.048023] CR2: 00000000000000c0 CR3: 0000000a83eb8004 CR4: 00000000007706e0<br /> [ 155758.062473] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000<br /> [ 155758.076924] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400<br /> [ 155758.091376] PKRU: 55555554<br /> [ 155758.096957] Call Trace:<br /> [ 155758.102016] <br /> [ 155758.106502] ? __die+0x78/0xc0<br /> [ 155758.112793] ? page_fault_oops+0x286/0x380<br /> [ 155758.121175] ? exc_page_fault+0x5d/0x110<br /> [ 155758.129209] ? asm_exc_page_fault+0x22/0x30<br /> [ 155758.137763] ? mem_cgroup_get_nr_swap_pages+0x3d/0xb0<br /> [ 155758.148060] workingset_test_recent+0xda/0x1b0<br /> [ 155758.157133] workingset_refault+0xca/0x1e0<br /> [ 155758.165508] filemap_add_folio+0x4d/0x70<br /> [ 155758.173538] page_cache_ra_unbounded+0xed/0x190<br /> [ 155758.182919] page_cache_sync_ra+0xd6/0x1e0<br /> [ 155758.191738] filemap_read+0x68d/0xdf0<br /> [ 155758.199495] ? mlx5e_napi_poll+0x123/0x940<br /> [ 155758.207981] ? __napi_schedule+0x55/0x90<br /> [ 155758.216095] __x64_sys_pread64+0x1d6/0x2c0<br /> [ 155758.224601] do_syscall_64+0x3d/0x80<br /> [ 155758.232058] entry_SYSCALL_64_after_hwframe+0x46/0xb0<br /> [ 155758.242473] RIP: 0033:0x7f62c29153b5<br /> [ 155758.249938] Code: e8 48 89 75 f0 89 7d f8 48 89 4d e0 e8 b4 e6 f7 ff 41 89 c0 4c 8b 55 e0 48 8b 55 e8 48 8b 75 f0 8b 7d f8 b8 11 00 00 00 0f 05 3d 00 f0 ff ff 77 33 44 89 c7 48 89 45 f8 e8 e7 e6 f7 ff 48 8b<br /> [ 155758.288005] RSP: 002b:00007f6234c5ffd0 EFLAGS: 00000293 ORIG_RAX: 0000000000000011<br /> [ 155758.303474] RAX: ffffffffffffffda RBX: 00007f628c4e70c0 RCX: 00007f62c29153b5<br /> [ 155758.318075] RDX: 000000000003c041 RSI: 00007f61d2986000 RDI: 0000000000000076<br /> [ 155758.332678] RBP: 00007f6234c5fff0 R08: 0000000000000000 R09: 0000000064d5230c<br /> [ 155758.347452] R10: 000000000027d450 R11: 0000000000000293 R12: 000000000003c041<br /> [ 155758.362044] R13: 00007f61d2986000 R14: 00007f629e11b060 R15: 000000000027d450<br /> [ 155758.376661] <br /> <br /> This patch fixes the issue by moving the memcg&amp;#39;s id publication from the<br /> alloc stage to <br /> ---truncated---