https://bugzilla.kernel.org/show_bug.cgi?id=199181 Bug ID: 199181 Summary: Out-of-bound access in ext4_valid_block_bitmap when mounting and operating on a 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 274877 --> https://bugzilla.kernel.org/attachment.cgi?id=274877&action=edit The crafted image which causes kernel panic - Overview Kernel crashes in ext4_valid_block_bitmap when mounting and operating a crafted ext4 image - Reproduce (under root) # mkdir mnt # mount -t ext4 230.img mnt # gcc -o poc poc.c # ./poc mnt - Reason https://elixir.bootlin.com/linux/v4.15/source/fs/ext4/balloc.c#L343 if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) /* bad block bitmap */ return blk; static inline int test_bit_le(int nr, const void *addr) { return test_bit(nr ^ BITOP_LE_SWIZZLE, addr); } static inline int test_bit(int nr, const volatile unsigned long *addr) { return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1))); } It seems kernel misses boundary check on BIT_WORD(nr), which causes out-of-bound access on addr (bh->b_data). - Kernel crash dump [ 262.162847] EXT4-fs (loop0): barriers disabled [ 262.167094] EXT4-fs (loop0): warning: mounting fs with errors, running e2fsck is recommended [ 262.167268] EXT4-fs (loop0): recovery complete [ 262.167271] EXT4-fs (loop0): mounted filesystem with ordered data mode. Opts: (null) [ 267.285863] EXT4-fs error (device loop0): ext4_readdir:183: inode #2: comm poc: path /home/wen/poc/mnt: directory contains a hole at offset 1024 [ 267.286057] BUG: unable to handle kernel paging request at ffff8b4bc81dc7f8 [ 267.286095] IP: ext4_validate_block_bitmap+0x196/0x350 [ 267.286116] PGD 1b13f067 P4D 1b13f067 PUD 0 [ 267.286137] Oops: 0000 [#1] SMP PTI [ 267.286160] 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 [ 267.286543] 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 [ 267.286650] CPU: 0 PID: 1344 Comm: poc Not tainted 4.15.0-12-generic #13-Ubuntu [ 267.286679] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/02/2015 [ 267.286727] RIP: 0010:ext4_validate_block_bitmap+0x196/0x350 [ 267.286751] RSP: 0018:ffffb90741703868 EFLAGS: 00010202 [ 267.286775] RAX: 000000007ffffffe RBX: ffff8b4bb91a1000 RCX: 0000000000000000 [ 267.286833] RDX: ffff8b4bb81dc800 RSI: ffff8b4bb81dc800 RDI: ffff8b4bb91a1000 [ 267.286862] RBP: ffffb907417038b8 R08: ffff8b4bb91a2000 R09: 000000007fffffff [ 267.286889] R10: ffff8b4bb81dc900 R11: ffffb90741703798 R12: 0000000000000000 [ 267.286917] R13: ffff8b4bb8e1e2d8 R14: 0000000000000000 R15: ffff8b4bb91a2000 [ 267.286946] FS: 00007fc90862d540(0000) GS:ffff8b4bbc600000(0000) knlGS:0000000000000000 [ 267.286976] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 267.287001] CR2: ffff8b4bc81dc7f8 CR3: 0000000038210006 CR4: 00000000001606f0 [ 267.287061] Call Trace: [ 267.287082] ? ext4_bg_num_gdb+0x7c/0x90 [ 267.287106] ext4_read_block_bitmap_nowait+0xa5/0x5e0 [ 267.287129] ext4_read_block_bitmap+0x19/0x50 [ 267.287712] ext4_free_blocks+0x1f1/0xb60 [ 267.288250] ? _cond_resched+0x19/0x40 [ 267.288785] ? __kmalloc+0x19b/0x220 [ 267.289265] ext4_ext_remove_space+0xb35/0x1200 [ 267.289732] ext4_ext_truncate+0x88/0xa0 [ 267.290127] ext4_truncate+0x363/0x400 [ 267.290514] ext4_setattr+0x95e/0x9d0 [ 267.290935] notify_change+0x2eb/0x440 [ 267.291322] ? ext4_xattr_security_set+0x30/0x30 [ 267.291703] do_truncate+0x73/0xc0 [ 267.292071] path_openat+0xf84/0x16c0 [ 267.292426] ? touch_atime+0x36/0xe0 [ 267.292769] do_filp_open+0x9b/0x110 [ 267.293102] ? __check_object_size+0xaf/0x1b0 [ 267.293427] ? __alloc_fd+0x46/0x170 [ 267.293742] do_sys_open+0x1bb/0x2c0 [ 267.294042] ? do_sys_open+0x1bb/0x2c0 [ 267.294332] ? _cond_resched+0x19/0x40 [ 267.294660] SyS_openat+0x14/0x20 [ 267.294941] do_syscall_64+0x73/0x130 [ 267.295208] entry_SYSCALL_64_after_hwframe+0x3d/0xa2 [ 267.295472] RIP: 0033:0x7fc90812ec8e [ 267.295723] RSP: 002b:00007ffc8c52e940 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 [ 267.295979] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc90812ec8e [ 267.296237] RDX: 0000000000000202 RSI: 000055ed620a42d0 RDI: 00000000ffffff9c [ 267.296495] RBP: 00007ffc8c52eb10 R08: 0000000000000003 R09: 0000000000000000 [ 267.296754] R10: 0000000000000000 R11: 0000000000000246 R12: 000055ed61d01d30 [ 267.297010] R13: 00007ffc8c52ec10 R14: 0000000000000000 R15: 0000000000000000 [ 267.297267] Code: 10 48 8b 75 d0 4c 89 45 b8 48 01 d0 48 89 45 c8 e8 d0 dc 04 00 4c 8b 45 b8 49 89 c1 2b 45 c8 49 8b 55 28 41 8b 48 54 d3 f8 48 98 <48> 0f a3 02 72 7b 4d 85 c9 0f 84 62 ff ff ff 48 8b 83 08 04 00 [ 267.298075] RIP: ext4_validate_block_bitmap+0x196/0x350 RSP: ffffb90741703868 [ 267.298347] CR2: ffff8b4bc81dc7f8 [ 267.298613] ---[ end trace 1ecf08f3cdf242f0 ]--- Reported by Wen Xu from SSlab, Gatech -- You are receiving this mail because: You are watching the assignee of the bug.
