On Sun 25-11-18 08:58:02, Pan Bian wrote: > The function ext2_xattr_set calls brelse(bh) to drop the reference count > of bh. After that, bh may be freed. However, following brelse(bh), > it reads bh->b_data via macro HDR(bh). This may result in a > use-after-free bug. This patch moves brelse(bh) after reading field. > > Signed-off-by: Pan Bian <bianpan2016@xxxxxxx> Thanks for the fix! I've added the patch to my tree. Honza > --- > fs/ext2/xattr.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c > index 62d9a659a..dd8f10d 100644 > --- a/fs/ext2/xattr.c > +++ b/fs/ext2/xattr.c > @@ -612,9 +612,9 @@ bad_block: ext2_error(sb, "ext2_xattr_set", > } > > cleanup: > - brelse(bh); > if (!(bh && header == HDR(bh))) > kfree(header); > + brelse(bh); > up_write(&EXT2_I(inode)->xattr_sem); > > return error; > -- > 2.7.4 > > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
