https://bugzilla.kernel.org/show_bug.cgi?id=199185 Bug ID: 199185 Summary: Invalid pointer reference in get_acl (fs/posix_acl.c) when mounting and operating crafted ext4 image Product: File System Version: 2.5 Kernel Version: 4.15.x Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: ext4 Assignee: fs_ext4@xxxxxxxxxxxxxxxxxxxx Reporter: wen.xu@xxxxxxxxxx Regression: No Created attachment 274887 --> https://bugzilla.kernel.org/attachment.cgi?id=274887&action=edit The crafted image which causes kernel panic - Overview Kernel references invalid pointer when mounting and later operating on a crafted ext4 image - Reproduce # mkdir mnt # mount -t ext4 136.img mnt # gcc -o poc poc.c # ./poc ./mnt - Reason https://elixir.bootlin.com/linux/v4.15/source/fs/posix_acl.c#L154 acl = inode->i_op->get_acl(inode, type); if (IS_ERR(acl)) { /* * Remove our sentinel so that we don't block future attempts * to cache the ACL. */ cmpxchg(p, sentinel, ACL_NOT_CACHED); return acl; } Interestingly, it seems ext4's get_acl can return 0xffffffffc0c0c0c0, which also bypasses the check `if (IS_ERR(acl))`. - Kernel dump [ 740.268286] EXT4-fs (loop0): warning: mounting unchecked fs, running e2fsck is recommended [ 740.268788] EXT4-fs (loop0): mounted filesystem without journal. Opts: (null) [ 750.149045] EXT4-fs error (device loop0): ext4_readdir:238: inode #2: block 44: comm poc: path /home/wen/data/ext4-kernel/20180311/get_acl/mnt: bad entry in directory: inode out of bounds - offset=12(12), inode=4294901762, rec_len=12, name_len=2 [ 750.166268] EXT4-fs error (device loop0): mb_free_blocks:1468: group 0, inode 16: block 1985:freeing already freed block (bit 1984); block bitmap corrupt. [ 750.166342] EXT4-fs error (device loop0): ext4_mb_generate_buddy:756: group 0, block bitmap and bg descriptor inconsistent: 960 vs 961 free clusters [ 750.166525] BUG: unable to handle kernel paging request at ffffffffc0c0c0c0 [ 750.166641] IP: get_acl+0x90/0x100 [ 750.166687] PGD 1aa0e067 P4D 1aa0e067 PUD 1aa10067 PMD 0 [ 750.166717] Oops: 0002 [#1] SMP PTI [ 750.166793] Modules linked in: vmw_balloon coretemp intel_rapl_perf input_leds joydev serio_raw snd_ens1371 btusb snd_ac97_codec uvcvideo btrtl videobuf2_vmalloc btbcm btintel gameport snd_rawmidi videobuf2_memops bluetooth videobuf2_v4l2 videobuf2_core snd_seq_device ac97_bus snd_pcm videodev media ecdh_generic snd_timer snd soundcore shpchp mac_hid vmw_vsock_vmci_transport vsock vmw_vmci sch_fq_codel ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi ip_tables x_tables autofs4 btrfs zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc aesni_intel aes_x86_64 crypto_simd glue_helper cryptd vmwgfx [ 750.167360] psmouse ttm drm_kms_helper mptspi mptscsih ahci libahci e1000 mptbase scsi_transport_spi syscopyarea sysfillrect sysimgblt fb_sys_fops drm i2c_piix4 pata_acpi [ 750.167462] CPU: 0 PID: 1322 Comm: poc Not tainted 4.15.0-12-generic #13-Ubuntu [ 750.167538] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/02/2015 [ 750.167636] RIP: 0010:get_acl+0x90/0x100 [ 750.167683] RSP: 0018:ffffb90740d27d18 EFLAGS: 00010286 [ 750.167708] RAX: ffffffffc0c0c0c0 RBX: ffffffffc0c0c0c0 RCX: 0000000000000000 [ 750.167793] RDX: 0000000000000001 RSI: ffff8b4bb91e8c20 RDI: 0000000000000000 [ 750.167847] RBP: ffffb90740d27d40 R08: 000000000002be00 R09: ffffffffa64ddca2 [ 750.167900] R10: ffff8b4bb8df8ea0 R11: 007a0000007a6162 R12: ffff8b4bb8e277e8 [ 750.167927] R13: ffff8b4bb6401701 R14: 0000000000008000 R15: ffff8b4bb8e277f8 [ 750.167955] FS: 00007fa818f7c540(0000) GS:ffff8b4bbc600000(0000) knlGS:0000000000000000 [ 750.168011] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 750.168868] CR2: ffffffffc0c0c0c0 CR3: 00000000391ee005 CR4: 00000000001606f0 [ 750.169437] Call Trace: [ 750.169944] posix_acl_chmod+0x51/0xf0 [ 750.170435] ext4_setattr+0x1f2/0x9d0 [ 750.170925] ? filename_lookup+0xf2/0x190 [ 750.171379] notify_change+0x2eb/0x440 [ 750.171826] chmod_common+0x16a/0x180 [ 750.172516] SyS_chmod+0x59/0xb0 [ 750.173215] do_syscall_64+0x73/0x130 [ 750.173902] entry_SYSCALL_64_after_hwframe+0x3d/0xa2 [ 750.174531] RIP: 0033:0x7fa818a7dac7 [ 750.175097] RSP: 002b:00007ffd57657478 EFLAGS: 00000207 ORIG_RAX: 000000000000005a [ 750.175644] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fa818a7dac7 [ 750.176178] RDX: 00007ffd576574d0 RSI: 0000000000000000 RDI: 0000558df83702f0 [ 750.176713] RBP: 00007ffd576575e0 R08: 0000000000000003 R09: 0000000000000000 [ 750.177219] R10: ffffffffffffdc2b R11: 0000000000000207 R12: 0000558df6212d30 [ 750.177719] R13: 00007ffd576576e0 R14: 0000000000000000 R15: 0000000000000000 [ 750.178157] Code: b1 2f 49 8b 44 24 20 48 8b 40 18 48 85 c0 74 40 44 89 f6 4c 89 e7 e8 30 43 92 00 48 3d 00 f0 ff ff 48 89 c3 77 55 48 85 c0 74 03 <3e> ff 00 4c 89 e8 3e 49 0f b1 1f 49 39 c5 75 26 48 89 d8 5b 41 [ 750.179468] RIP: get_acl+0x90/0x100 RSP: ffffb90740d27d18 [ 750.179889] CR2: ffffffffc0c0c0c0 [ 750.180295] ---[ end trace 1ecf08f3cdf242f0 ]--- -- You are receiving this mail because: You are watching the assignee of the bug.
