| Message ID | 20210920194109.18976-4-kelsey.skunberg@canonical.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [SRU,B/F/H/I/OEM-5.10/HWE-5.8,1/1] ext4: fix race writing to an inline_data file while its xattrs are changing | expand |
Sigh. wasn't paying attention closely enough and sent the wrong saved patch. ignore this please :) On 2021-09-20 13:41:09 , Kelsey Skunberg wrote: > From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> > > From: Theodore Ts'o <tytso@mit.edu> > > The location of the system.data extended attribute can change whenever > xattr_sem is not taken. So we need to recalculate the i_inline_off > field since it mgiht have changed between ext4_write_begin() and > ext4_write_end(). > > This means that caching i_inline_off is probably not helpful, so in > the long run we should probably get rid of it and shrink the in-memory > ext4 inode slightly, but let's fix the race the simple way for now. > > Cc: stable@kernel.org > Fixes: f19d5870cbf72 ("ext4: add normal write support for inline data") > Reported-by: syzbot+13146364637c7363a7de@syzkaller.appspotmail.com > Signed-off-by: Theodore Ts'o <tytso@mit.edu> > (cherry picked from commit a54c4613dac1500b40e4ab55199f7c51f028e848) > CVE-2021-40490 > Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> > --- > fs/ext4/inline.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c > index 6c95196a6f80..952c3e1715d4 100644 > --- a/fs/ext4/inline.c > +++ b/fs/ext4/inline.c > @@ -750,6 +750,12 @@ int ext4_write_inline_data_end(struct inode *inode, loff_t pos, unsigned len, > ext4_write_lock_xattr(inode, &no_expand); > BUG_ON(!ext4_has_inline_data(inode)); > > + /* > + * ei->i_inline_off may have changed since ext4_write_begin() > + * called ext4_try_to_write_inline_data() > + */ > + (void) ext4_find_inline_data_nolock(inode); > + > kaddr = kmap_atomic(page); > ext4_write_inline_data(inode, &iloc, kaddr, pos, len); > kunmap_atomic(kaddr); > -- > 2.30.2 > > > -- > kernel-team mailing list > kernel-team@lists.ubuntu.com > https://lists.ubuntu.com/mailman/listinfo/kernel-team
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index 6c95196a6f80..952c3e1715d4 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -750,6 +750,12 @@ int ext4_write_inline_data_end(struct inode *inode, loff_t pos, unsigned len, ext4_write_lock_xattr(inode, &no_expand); BUG_ON(!ext4_has_inline_data(inode)); + /* + * ei->i_inline_off may have changed since ext4_write_begin() + * called ext4_try_to_write_inline_data() + */ + (void) ext4_find_inline_data_nolock(inode); + kaddr = kmap_atomic(page); ext4_write_inline_data(inode, &iloc, kaddr, pos, len); kunmap_atomic(kaddr);