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Subject[PATCH] ntfs: move check for valid resident attribute offset and length
Date
we should check for valid resident atribute offset and length before
loading STANDARD_INFORMATION attribute in ntfs_read_locked_inode()
let's make that check a bit earlier in the same function to avoid
use-after-free bug

Reported-and-tested-by: syzbot+c584225dabdea2f71969@syzkaller.appspotmail.com
Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>
Link: https://syzkaller.appspot.com/bug?extid=c584225dabdea2f71969
---
fs/ntfs/inode.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c
index f7e4cbc26eaf..70745aea5106 100644
--- a/fs/ntfs/inode.c
+++ b/fs/ntfs/inode.c
@@ -629,6 +629,13 @@ static int ntfs_read_locked_inode(struct inode *vi)
}
a = ctx->attr;
/* Get the standard information attribute value. */
+ if ((u8 *)a + le16_to_cpu(a->data.resident.value_offset)
+ + le32_to_cpu(
+ a->data.resident.value_length) >
+ (u8 *)ctx->mrec + vol->mft_record_size) {
+ ntfs_error(vi->i_sb, "Corrupt attribute list in inode.");
+ goto unm_err_out;
+ }
si = (STANDARD_INFORMATION*)((u8*)a +
le16_to_cpu(a->data.resident.value_offset));

@@ -731,14 +738,6 @@ static int ntfs_read_locked_inode(struct inode *vi)
goto unm_err_out;
}
} else /* if (!a->non_resident) */ {
- if ((u8*)a + le16_to_cpu(a->data.resident.value_offset)
- + le32_to_cpu(
- a->data.resident.value_length) >
- (u8*)ctx->mrec + vol->mft_record_size) {
- ntfs_error(vi->i_sb, "Corrupt attribute list "
- "in inode.");
- goto unm_err_out;
- }
/* Now copy the attribute list. */
memcpy(ni->attr_list, (u8*)a + le16_to_cpu(
a->data.resident.value_offset),
--
2.30.0
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