| Message ID | 20240801151740.339272-1-lizhi.xu@windriver.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [V2] squashfs: Add length check in squashfs_symlink_read_folio | expand |
On Thu 01-08-24 23:17:40, Lizhi Xu wrote: > syzbot report KMSAN: uninit-value in pick_link, the root cause is that > squashfs_symlink_read_folio did not check the length, resulting in folio > not being initialized and did not return the corresponding error code. > > The incorrect value of length is due to the incorrect value of inode->i_size. > > Reported-and-tested-by: syzbot+24ac24ff58dc5b0d26b9@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=24ac24ff58dc5b0d26b9 > Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com> > --- > fs/squashfs/symlink.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/fs/squashfs/symlink.c b/fs/squashfs/symlink.c > index 6ef735bd841a..d5fa5165ddd6 100644 > --- a/fs/squashfs/symlink.c > +++ b/fs/squashfs/symlink.c > @@ -61,6 +61,12 @@ static int squashfs_symlink_read_folio(struct file *file, struct folio *folio) > } > } > > + if (length < 0) { OK, so this would mean that (int)inode->i_size is a negative number. Possible. Perhaps we should rather better validate i_size of symlinks in squashfs_read_inode()? Otherwise it would be a whack-a-mole game of catching places that get confused by bogus i_size... Honza > + ERROR("Unable to read symlink, wrong length [%d]\n", length); > + error = -EINVAL; > + goto out; > + } > + > /* > * Read length bytes from symlink metadata. Squashfs_read_metadata > * is not used here because it can sleep and we want to use > -- > 2.43.0 >
On Thu, 1 Aug 2024 17:30:42 +0200, Jan Kara wrote: > > syzbot report KMSAN: uninit-value in pick_link, the root cause is that > > squashfs_symlink_read_folio did not check the length, resulting in folio > > not being initialized and did not return the corresponding error code. > > > > The incorrect value of length is due to the incorrect value of inode->i_size. > > > > Reported-and-tested-by: syzbot+24ac24ff58dc5b0d26b9@syzkaller.appspotmail.com > > Closes: https://syzkaller.appspot.com/bug?extid=24ac24ff58dc5b0d26b9 > > Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com> > > --- > > fs/squashfs/symlink.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/fs/squashfs/symlink.c b/fs/squashfs/symlink.c > > index 6ef735bd841a..d5fa5165ddd6 100644 > > --- a/fs/squashfs/symlink.c > > +++ b/fs/squashfs/symlink.c > > @@ -61,6 +61,12 @@ static int squashfs_symlink_read_folio(struct file *file, struct folio *folio) > > } > > } > > > > + if (length < 0) { > > OK, so this would mean that (int)inode->i_size is a negative number. > Possible. Perhaps we should rather better validate i_size of symlinks in > squashfs_read_inode()? Otherwise it would be a whack-a-mole game of > catching places that get confused by bogus i_size... This move is tough enough, start from where i_size is initialized. I will send a v3 patch for it. -- Lizhi
diff --git a/fs/squashfs/symlink.c b/fs/squashfs/symlink.c index 6ef735bd841a..d5fa5165ddd6 100644 --- a/fs/squashfs/symlink.c +++ b/fs/squashfs/symlink.c @@ -61,6 +61,12 @@ static int squashfs_symlink_read_folio(struct file *file, struct folio *folio) } } + if (length < 0) { + ERROR("Unable to read symlink, wrong length [%d]\n", length); + error = -EINVAL; + goto out; + } + /* * Read length bytes from symlink metadata. Squashfs_read_metadata * is not used here because it can sleep and we want to use
syzbot report KMSAN: uninit-value in pick_link, the root cause is that squashfs_symlink_read_folio did not check the length, resulting in folio not being initialized and did not return the corresponding error code. The incorrect value of length is due to the incorrect value of inode->i_size. Reported-and-tested-by: syzbot+24ac24ff58dc5b0d26b9@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=24ac24ff58dc5b0d26b9 Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com> --- fs/squashfs/symlink.c | 6 ++++++ 1 file changed, 6 insertions(+)