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authorTheodore Ts'o <tytso@mit.edu>2018-04-01 23:21:03 -0400
committerTheodore Ts'o <tytso@mit.edu>2018-04-01 23:21:03 -0400
commite40ff213898502d299351cc2fe1e350cd186f0d3 (patch)
tree48d024ff8abaa9efca5d38d93602188211c0130a /fs/ext4
parent54dd0e0a1b255f115f8647fc6fb93273251b01b9 (diff)
downloadlinux-e40ff213898502d299351cc2fe1e350cd186f0d3.tar.bz2
ext4: force revalidation of directory pointer after seekdir(2)
A malicious user could force the directory pointer to be in an invalid spot by using seekdir(2). Use the mechanism we already have to notice if the directory has changed since the last time we called ext4_readdir() to force a revalidation of the pointer. Reported-by: syzbot+1236ce66f79263e8a862@syzkaller.appspotmail.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/dir.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index da87cf757f7d..e2902d394f1b 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -365,13 +365,15 @@ static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
{
struct inode *inode = file->f_mapping->host;
int dx_dir = is_dx_dir(inode);
- loff_t htree_max = ext4_get_htree_eof(file);
+ loff_t ret, htree_max = ext4_get_htree_eof(file);
if (likely(dx_dir))
- return generic_file_llseek_size(file, offset, whence,
+ ret = generic_file_llseek_size(file, offset, whence,
htree_max, htree_max);
else
- return ext4_llseek(file, offset, whence);
+ ret = ext4_llseek(file, offset, whence);
+ file->f_version = inode_peek_iversion(inode) - 1;
+ return ret;
}
/*