From: Jan Kara Date: Thu, 21 May 2015 14:05:56 +0000 (+0200) Subject: xfs: Correctly lock inode when removing suid and file capabilities X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=a6de82cab123beaf9406024943caa0242f0618b0;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git xfs: Correctly lock inode when removing suid and file capabilities Currently XFS calls file_remove_privs() without holding i_mutex. This is wrong because that function can end up messing with file permissions and file capabilities stored in xattrs for which we need i_mutex held. Fix the problem by grabbing iolock exclusively when we will need to change anything in permissions / xattrs. Reviewed-by: Dave Chinner Signed-off-by: Jan Kara Signed-off-by: Al Viro --- diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index f3e4fbb59985..71c2c712e609 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -563,6 +563,13 @@ restart: if (error) return error; + /* For changing security info in file_remove_privs() we need i_mutex */ + if (*iolock == XFS_IOLOCK_SHARED && !IS_NOSEC(inode)) { + xfs_rw_iunlock(ip, *iolock); + *iolock = XFS_IOLOCK_EXCL; + xfs_rw_ilock(ip, *iolock); + goto restart; + } /* * If the offset is beyond the size of the file, we need to zero any * blocks that fall between the existing EOF and the start of this @@ -623,7 +630,9 @@ restart: * setgid bits if the process is not being run by root. This keeps * people from modifying setuid and setgid binaries. */ - return file_remove_privs(file); + if (!IS_NOSEC(inode)) + return file_remove_privs(file); + return 0; } /*