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chaseyuJaegeuk Kim
chaseyu
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Jaegeuk Kim
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f2fs: fix invalid memory access
syzbot found the following crash on: HEAD commit: d9bd94c Add linux-next specific files for 20180801 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=1001189c400000 kernel config: https://syzkaller.appspot.com/x/.config?x=cc8964ea4d04518c dashboard link: https://syzkaller.appspot.com/bug?extid=c966a82db0b14aa37e81 compiler: gcc (GCC) 8.0.1 20180413 (experimental) Unfortunately, I don't have any reproducer for this crash yet. IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: [email protected] loop7: rw=12288, want=8200, limit=20 netlink: 65342 bytes leftover after parsing attributes in process `syz-executor4'. openvswitch: netlink: Message has 8 unknown bytes. kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN CPU: 1 PID: 7615 Comm: syz-executor7 Not tainted 4.18.0-rc7-next-20180801+ #29 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__read_once_size include/linux/compiler.h:188 [inline] RIP: 0010:compound_head include/linux/page-flags.h:142 [inline] RIP: 0010:PageLocked include/linux/page-flags.h:272 [inline] RIP: 0010:f2fs_put_page fs/f2fs/f2fs.h:2011 [inline] RIP: 0010:validate_checkpoint+0x66d/0xec0 fs/f2fs/checkpoint.c:835 Code: e8 58 05 7f fe 4c 8d 6b 80 4d 8d 74 24 08 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 c6 04 02 00 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 f4 06 00 00 4c 89 ea 4d 8b 7c 24 08 48 b8 00 00 RSP: 0018:ffff8801937cebe8 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff8801937cef30 RCX: ffffc90006035000 RDX: 0000000000000000 RSI: ffffffff82fd9658 RDI: 0000000000000005 RBP: ffff8801937cef58 R08: ffff8801ab254700 R09: fffff94000d9e026 R10: fffff94000d9e026 R11: ffffea0006cf0137 R12: fffffffffffffffb R13: ffff8801937ceeb0 R14: 0000000000000003 R15: ffff880193419b40 FS: 00007f36a61d5700(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc04ff93000 CR3: 00000001d0562000 CR4: 00000000001426e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: f2fs_get_valid_checkpoint+0x436/0x1ec0 fs/f2fs/checkpoint.c:860 f2fs_fill_super+0x2d42/0x8110 fs/f2fs/super.c:2883 mount_bdev+0x314/0x3e0 fs/super.c:1344 f2fs_mount+0x3c/0x50 fs/f2fs/super.c:3133 legacy_get_tree+0x131/0x460 fs/fs_context.c:729 vfs_get_tree+0x1cb/0x5c0 fs/super.c:1743 do_new_mount fs/namespace.c:2603 [inline] do_mount+0x6f2/0x1e20 fs/namespace.c:2927 ksys_mount+0x12d/0x140 fs/namespace.c:3143 __do_sys_mount fs/namespace.c:3157 [inline] __se_sys_mount fs/namespace.c:3154 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3154 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45943a Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 bd 8a fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 9a 8a fb ff c3 66 0f 1f 84 00 00 00 00 00 RSP: 002b:00007f36a61d4a88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f36a61d4b30 RCX: 000000000045943a RDX: 00007f36a61d4ad0 RSI: 0000000020000100 RDI: 00007f36a61d4af0 RBP: 0000000020000100 R08: 00007f36a61d4b30 R09: 00007f36a61d4ad0 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000013 R13: 0000000000000000 R14: 00000000004c8ea0 R15: 0000000000000000 Modules linked in: Dumping ftrace buffer: (ftrace buffer empty) ---[ end trace bd8550c129352286 ]--- RIP: 0010:__read_once_size include/linux/compiler.h:188 [inline] RIP: 0010:compound_head include/linux/page-flags.h:142 [inline] RIP: 0010:PageLocked include/linux/page-flags.h:272 [inline] RIP: 0010:f2fs_put_page fs/f2fs/f2fs.h:2011 [inline] RIP: 0010:validate_checkpoint+0x66d/0xec0 fs/f2fs/checkpoint.c:835 Code: e8 58 05 7f fe 4c 8d 6b 80 4d 8d 74 24 08 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 c6 04 02 00 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 f4 06 00 00 4c 89 ea 4d 8b 7c 24 08 48 b8 00 00 RSP: 0018:ffff8801937cebe8 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff8801937cef30 RCX: ffffc90006035000 RDX: 0000000000000000 RSI: ffffffff82fd9658 RDI: 0000000000000005 netlink: 65342 bytes leftover after parsing attributes in process `syz-executor4'. RBP: ffff8801937cef58 R08: ffff8801ab254700 R09: fffff94000d9e026 openvswitch: netlink: Message has 8 unknown bytes. R10: fffff94000d9e026 R11: ffffea0006cf0137 R12: fffffffffffffffb R13: ffff8801937ceeb0 R14: 0000000000000003 R15: ffff880193419b40 FS: 00007f36a61d5700(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc04ff93000 CR3: 00000001d0562000 CR4: 00000000001426e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 In validate_checkpoint(), if we failed to call get_checkpoint_version(), we will pass returned invalid page pointer into f2fs_put_page, cause accessing invalid memory, this patch tries to handle error path correctly to fix this issue. Signed-off-by: Chao Yu <[email protected]> Signed-off-by: Jaegeuk Kim <[email protected]>
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‎fs/f2fs/checkpoint.c‎

Lines changed: 6 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -780,13 +780,15 @@ static int get_checkpoint_version(struct f2fs_sb_info *sbi, block_t cp_addr,
780780

781781
crc_offset = le32_to_cpu((*cp_block)->checksum_offset);
782782
if (crc_offset > (blk_size - sizeof(__le32))) {
783+
f2fs_put_page(*cp_page, 1);
783784
f2fs_msg(sbi->sb, KERN_WARNING,
784785
"invalid crc_offset: %zu", crc_offset);
785786
return -EINVAL;
786787
}
787788

788789
crc = cur_cp_crc(*cp_block);
789790
if (!f2fs_crc_valid(sbi, crc, *cp_block, crc_offset)) {
791+
f2fs_put_page(*cp_page, 1);
790792
f2fs_msg(sbi->sb, KERN_WARNING, "invalid crc value");
791793
return -EINVAL;
792794
}
@@ -806,32 +808,31 @@ static struct page *validate_checkpoint(struct f2fs_sb_info *sbi,
806808
err = get_checkpoint_version(sbi, cp_addr, &cp_block,
807809
&cp_page_1, version);
808810
if (err)
809-
goto invalid_cp1;
811+
return NULL;
810812

811813
if (le32_to_cpu(cp_block->cp_pack_total_block_count) >
812814
sbi->blocks_per_seg) {
813815
f2fs_msg(sbi->sb, KERN_WARNING,
814816
"invalid cp_pack_total_block_count:%u",
815817
le32_to_cpu(cp_block->cp_pack_total_block_count));
816-
goto invalid_cp1;
818+
goto invalid_cp;
817819
}
818820
pre_version = *version;
819821

820822
cp_addr += le32_to_cpu(cp_block->cp_pack_total_block_count) - 1;
821823
err = get_checkpoint_version(sbi, cp_addr, &cp_block,
822824
&cp_page_2, version);
823825
if (err)
824-
goto invalid_cp2;
826+
goto invalid_cp;
825827
cur_version = *version;
826828

827829
if (cur_version == pre_version) {
828830
*version = cur_version;
829831
f2fs_put_page(cp_page_2, 1);
830832
return cp_page_1;
831833
}
832-
invalid_cp2:
833834
f2fs_put_page(cp_page_2, 1);
834-
invalid_cp1:
835+
invalid_cp:
835836
f2fs_put_page(cp_page_1, 1);
836837
return NULL;
837838
}

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