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authorAlexander Lochmann <alexander.lochmann@tu-dortmund.de>2018-12-14 11:55:52 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-06-22 08:16:19 +0200
commit2c54624255635a4f421fef9c7692f7fc9314b453 (patch)
tree6b30e5baaf78fd5d81f2e271b9d4eeaaf8decdf2
parent7ab0cb70c2d2c7615b2b489d55e850cdae5400ef (diff)
Abort file_remove_privs() for non-reg. files
commit f69e749a49353d96af1a293f56b5b56de59c668a upstream. file_remove_privs() might be called for non-regular files, e.g. blkdev inode. There is no reason to do its job on things like blkdev inodes, pipes, or cdevs. Hence, abort if file does not refer to a regular inode. AV: more to the point, for devices there might be any number of inodes refering to given device. Which one to strip the permissions from, even if that made any sense in the first place? All of them will be observed with contents modified, after all. Found by LockDoc (Alexander Lochmann, Horst Schirmeier and Olaf Spinczyk) Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Alexander Lochmann <alexander.lochmann@tu-dortmund.de> Signed-off-by: Horst Schirmeier <horst.schirmeier@tu-dortmund.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Zubin Mithra <zsm@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/inode.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/inode.c b/fs/inode.c
index cfc36d11bcb3..76f7535fe754 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1817,8 +1817,13 @@ int file_remove_privs(struct file *file)
int kill;
int error = 0;
- /* Fast path for nothing security related */
- if (IS_NOSEC(inode))
+ /*
+ * Fast path for nothing security related.
+ * As well for non-regular files, e.g. blkdev inodes.
+ * For example, blkdev_write_iter() might get here
+ * trying to remove privs which it is not allowed to.
+ */
+ if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode))
return 0;
kill = dentry_needs_remove_privs(dentry);