From: Bryan Wu This bug was caught by LTP testcase fchmod06 on Blackfin platform. In the manpage of fchmod, "EPERM: The effective UID does not match the owner of the file, and the process is not privileged (Linux: it does not have the CAP_FOWNER capability)." But the ramfs nommu code missed the inode_change_ok POSIX UID/GID verification. This patch fixed this. Signed-off-by: Bryan Wu Cc: David Howells Signed-off-by: Andrew Morton --- fs/ramfs/file-nommu.c | 5 +++++ 1 file changed, 5 insertions(+) diff -puN fs/ramfs/file-nommu.c~ramfs-nommu-missed-posix-uid-gid-inode-attribute-checking fs/ramfs/file-nommu.c --- a/fs/ramfs/file-nommu.c~ramfs-nommu-missed-posix-uid-gid-inode-attribute-checking +++ a/fs/ramfs/file-nommu.c @@ -195,6 +195,11 @@ static int ramfs_nommu_setattr(struct de unsigned int old_ia_valid = ia->ia_valid; int ret = 0; + /* POSIX UID/GID verification for setting inode attributes */ + ret = inode_change_ok(inode, ia); + if (ret) + return ret; + /* by providing our own setattr() method, we skip this quotaism */ if ((old_ia_valid & ATTR_UID && ia->ia_uid != inode->i_uid) || (old_ia_valid & ATTR_GID && ia->ia_gid != inode->i_gid)) _