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Message-ID: <48493318-c2e2-ee09-35e6-1b758ccdf3e5@kernel.org>
Date: Thu, 2 Aug 2018 07:29:45 +0800
From: Chao Yu <chao@...nel.org>
To: Jaegeuk Kim <jaegeuk@...nel.org>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, Chao Yu <yuchao0@...wei.com>
Subject: Re: [PATCH] f2fs: fix invalid memory access
On 2018/8/2 2:58, Jaegeuk Kim wrote:
> On 08/01, Chao Yu wrote:
>> From: Chao Yu <yuchao0@...wei.com>
>>
>> syzbot found the following crash on:
>>
>> HEAD commit: d9bd94c0bcaa 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: syzbot+c966a82db0b14aa37e81@...kaller.appspotmail.com
>>
>> 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 <yuchao0@...wei.com>
>> ---
>> fs/f2fs/checkpoint.c | 12 ++++++------
>> 1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>> index 2cffc37e6c5b..861e61e08aa6 100644
>> --- a/fs/f2fs/checkpoint.c
>> +++ b/fs/f2fs/checkpoint.c
>> @@ -780,6 +780,7 @@ static int get_checkpoint_version(struct f2fs_sb_info *sbi, block_t cp_addr,
>>
>> crc_offset = le32_to_cpu((*cp_block)->checksum_offset);
>> if (crc_offset > (blk_size - sizeof(__le32))) {
>> + f2fs_put_page(*cp_page, 1);
>> f2fs_msg(sbi->sb, KERN_WARNING,
>> "invalid crc_offset: %zu", crc_offset);
>> return -EINVAL;
>> @@ -787,6 +788,7 @@ static int get_checkpoint_version(struct f2fs_sb_info *sbi, block_t cp_addr,
>>
>> crc = cur_cp_crc(*cp_block);
>> if (!f2fs_crc_valid(sbi, crc, *cp_block, crc_offset)) {
>> + f2fs_put_page(*cp_page, 1);
>> f2fs_msg(sbi->sb, KERN_WARNING, "invalid crc value");
>> return -EINVAL;
>> }
>> @@ -806,14 +808,14 @@ static struct page *validate_checkpoint(struct f2fs_sb_info *sbi,
>> err = get_checkpoint_version(sbi, cp_addr, &cp_block,
>> &cp_page_1, version);
>> if (err)
>> - goto invalid_cp1;
>> + return NULL;
>>
>> if (le32_to_cpu(cp_block->cp_pack_total_block_count) >
>> sbi->log_blocks_per_seg) {
>> f2fs_msg(sbi->sb, KERN_WARNING,
>> "invalid cp_pack_total_block_count:%u",
>> le32_to_cpu(cp_block->cp_pack_total_block_count));
>> - goto invalid_cp1;
>> + goto invalid_cp;
>> }
>> pre_version = *version;
>>
>> @@ -821,7 +823,7 @@ static struct page *validate_checkpoint(struct f2fs_sb_info *sbi,
>> err = get_checkpoint_version(sbi, cp_addr, &cp_block,
>> &cp_page_2, version);
>> if (err)
>> - goto invalid_cp2;
>> + goto invalid_cp;
>> cur_version = *version;
>>
>> if (cur_version == pre_version) {
>> @@ -829,9 +831,7 @@ static struct page *validate_checkpoint(struct f2fs_sb_info *sbi,
>> f2fs_put_page(cp_page_2, 1);
>> return cp_page_1;
>> }
>> -invalid_cp2:
>> - f2fs_put_page(cp_page_2, 1);
>
> we need to put cp_page_2 above.
Yes, let me update it in v2.
Thanks,
>
>> -invalid_cp1:
>> +invalid_cp:
>> f2fs_put_page(cp_page_1, 1);
>> return NULL;
>> }
>> --
>> 2.18.0
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