https://bugzilla.kernel.org/show_bug.cgi?id=215227 Bug ID: 215227 Summary: FUZZ: Page fault in fs/ext4/namei.c: do_split when crafted image is mounted and operated Product: File System Version: 2.5 Kernel Version: 5.16.0-rc3 Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: ext4 Assignee: fs_ext4@xxxxxxxxxxxxxxxxxxxx Reporter: tytso@xxxxxxx Regression: No Created attachment 299903 --> https://bugzilla.kernel.org/attachment.cgi?id=299903&action=edit tmp173 Original report: https://lore.kernel.org/r/CA+AJg7NwCgxw65JbyWLbbq4aP-vbBzFMEn-=k6DrdTpWMBQbxQ@xxxxxxxxxxxxxx From: Liu Wenqing <wenqingliu0120@xxxxxxxxx> - Overview A page fault occurs in fs/ext4/namei.c: do_split when a crafted image is mounted and operated. - Reproduce tested on kernel 5.16-rc3, 5.15.X, 5.14.X under root # mkdir mnt # mount -t ext4 tmp173.img mnt # gcc -o tmp173 tmp173.c # cp tmp173 mnt # cd mnt # ./tmp173 -Reason Seems to be an integer underflow https://elixir.bootlin.com/linux/v5.16-rc3/source/fs/ext4/namei.c#L1973 - Kernel dump [ 68.084727] loop0: detected capacity change from 0 to 32768 [ 68.115775] EXT4-fs (loop0): mounted filesystem with ordered data mode. Opts: (null). Quota mode: none. [ 68.115793] ext4 filesystem being mounted at /home/wq/test_crashes/crash_tests/mnt supports timestamps until 2038 (0x7fffffff) [ 80.025429] BUG: unable to handle page fault for address: ffff88891e93dbf0 [ 80.025461] #PF: supervisor read access in kernel mode [ 80.025472] #PF: error_code(0x0000) - not-present page [ 80.025483] PGD 3401067 P4D 3401067 PUD 0 [ 80.025493] Oops: 0000 [#1] PREEMPT SMP NOPTI [ 80.025505] CPU: 1 PID: 920 Comm: tmp173 Not tainted 5.16.0-rc3 #2 [ 80.025518] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014 [ 80.025534] RIP: 0010:do_split+0x3be/0x8b0 [ 80.025564] Code: c8 44 39 d0 0f 87 d0 03 00 00 41 83 e8 01 01 d1 41 83 c1 01 41 83 f8 ff 75 d6 44 89 f8 d1 e8 89 c2 8d 48 ff 48 8d 14 d6 8b 3a <39> 3c ce 89 7c 24 38 40 0f 94 c7 81 7c 24 18 00 00 04 00 40 0f b6 [ 80.025598] RSP: 0018:ffffc90000c6fbf8 EFLAGS: 00010247 [ 80.025609] RAX: 0000000000000000 RBX: ffff888105995730 RCX: 00000000ffffffff [ 80.025623] RDX: ffff88811e93dbf8 RSI: ffff88811e93dbf8 RDI: 0000000040ab9e92 [ 80.025637] RBP: ffff888105c3f000 R08: 00000000ffffffff R09: 0000000000000001 [ 80.025650] R10: 0000000000000200 R11: 00000000a0b6181c R12: ffffc90000c6fcf8 [ 80.025664] R13: ffff88811e93dc00 R14: ffff88811e93dbf8 R15: 0000000000000001 [ 80.025678] FS: 00007fb08a0f64c0(0000) GS:ffff8882f5c80000(0000) knlGS:0000000000000000 [ 80.025696] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 80.025707] CR2: ffff88891e93dbf0 CR3: 000000010a7f4006 CR4: 0000000000370ee0 [ 80.025723] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 80.025736] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 80.025750] Call Trace: [ 80.025756] <TASK> [ 80.025763] make_indexed_dir+0x487/0x5d0 [ 80.025775] ext4_add_entry+0x376/0x410 [ 80.025788] ext4_add_nondir+0x2b/0xc0 [ 80.025798] ext4_symlink+0x2aa/0x450 [ 80.025807] vfs_symlink+0x105/0x1a0 [ 80.025821] do_symlinkat+0xde/0xf0 [ 80.025830] __x64_sys_symlink+0x37/0x40 [ 80.025839] do_syscall_64+0x37/0xb0 [ 80.025857] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 80.025870] RIP: 0033:0x7fb089c00639 [ 80.025878] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 1f f8 2c 00 f7 d8 64 89 01 48 [ 80.025912] RSP: 002b:00007fffcbbbe558 EFLAGS: 00000286 ORIG_RAX: 0000000000000058 [ 80.025928] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb089c00639 [ 80.025941] RDX: ffffffffffffff80 RSI: 00007fffcbbbe700 RDI: 00007fffcbbbe5e4 [ 80.025955] RBP: 00007fffcbbc0910 R08: 00007fffcbbc09f8 R09: 00007fffcbbc09f8 [ 80.025968] R10: 00007fffcbbc09f8 R11: 0000000000000286 R12: 000055f1994005f0 [ 80.025982] R13: 00007fffcbbc09f0 R14: 0000000000000000 R15: 0000000000000000 [ 80.025996] </TASK> [ 80.026001] Modules linked in: joydev input_leds serio_raw qemu_fw_cfg iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi autofs4 btrfs blake2b_generic zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq raid1 raid0 multipath linear qxl drm_ttm_helper ttm drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel hid_generic psmouse usbhid aesni_intel crypto_simd cryptd hid [ 80.026946] CR2: ffff88891e93dbf0 [ 80.027378] ---[ end trace f76e3850025c0375 ]--- [ 80.027803] RIP: 0010:do_split+0x3be/0x8b0 [ 80.028243] Code: c8 44 39 d0 0f 87 d0 03 00 00 41 83 e8 01 01 d1 41 83 c1 01 41 83 f8 ff 75 d6 44 89 f8 d1 e8 89 c2 8d 48 ff 48 8d 14 d6 8b 3a <39> 3c ce 89 7c 24 38 40 0f 94 c7 81 7c 24 18 00 00 04 00 40 0f b6 [ 80.029143] RSP: 0018:ffffc90000c6fbf8 EFLAGS: 00010247 [ 80.029602] RAX: 0000000000000000 RBX: ffff888105995730 RCX: 00000000ffffffff [ 80.030064] RDX: ffff88811e93dbf8 RSI: ffff88811e93dbf8 RDI: 0000000040ab9e92 [ 80.030521] RBP: ffff888105c3f000 R08: 00000000ffffffff R09: 0000000000000001 [ 80.030992] R10: 0000000000000200 R11: 00000000a0b6181c R12: ffffc90000c6fcf8 [ 80.031430] R13: ffff88811e93dc00 R14: ffff88811e93dbf8 R15: 0000000000000001 [ 80.031861] FS: 00007fb08a0f64c0(0000) GS:ffff8882f5c80000(0000) knlGS:0000000000000000 [ 80.032293] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 80.032724] CR2: ffff88891e93dbf0 CR3: 000000010a7f4006 CR4: 0000000000370ee0 [ 80.033167] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 80.033604] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Thanks, Wenqing Liu -- You may reply to this email to add a comment. 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