aboutsummaryrefslogtreecommitdiffstats
path: root/fs/fcntl.c
diff options
context:
space:
mode:
authorJiri Slaby <jslaby@suse.cz>2017-06-13 13:35:51 +0200
committerJeff Layton <jlayton@redhat.com>2017-06-14 08:46:45 -0400
commitfc3dc67471461c0efcb1ed22fb7595121d65fad9 (patch)
tree6f1fa906e1e74da646bcf0511ad71a849e4a8302 /fs/fcntl.c
parentfs/fcntl: f_setown, allow returning error (diff)
downloadlinux-dev-fc3dc67471461c0efcb1ed22fb7595121d65fad9.tar.xz
linux-dev-fc3dc67471461c0efcb1ed22fb7595121d65fad9.zip
fs/fcntl: f_setown, avoid undefined behaviour
fcntl(0, F_SETOWN, 0x80000000) triggers: UBSAN: Undefined behaviour in fs/fcntl.c:118:7 negation of -2147483648 cannot be represented in type 'int': CPU: 1 PID: 18261 Comm: syz-executor Not tainted 4.8.1-0-syzkaller #1 ... Call Trace: ... [<ffffffffad8f0868>] ? f_setown+0x1d8/0x200 [<ffffffffad8f19a9>] ? SyS_fcntl+0x999/0xf30 [<ffffffffaed1fb00>] ? entry_SYSCALL_64_fastpath+0x23/0xc1 Fix that by checking the arg parameter properly (against INT_MAX) before "who = -who". And return immediatelly with -EINVAL in case it is wrong. Note that according to POSIX we can return EINVAL: http://pubs.opengroup.org/onlinepubs/9699919799/functions/fcntl.html [EINVAL] The cmd argument is F_SETOWN and the value of the argument is not valid as a process or process group identifier. [v2] returns an error, v1 used to fail silently [v3] implement proper check for the bad value INT_MIN Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Jeff Layton <jlayton@poochiereds.net> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Signed-off-by: Jeff Layton <jlayton@redhat.com>
Diffstat (limited to 'fs/fcntl.c')
-rw-r--r--fs/fcntl.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/fcntl.c b/fs/fcntl.c
index 313eba860346..693322e28751 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -116,6 +116,10 @@ int f_setown(struct file *filp, unsigned long arg, int force)
int who = arg;
type = PIDTYPE_PID;
if (who < 0) {
+ /* avoid overflow below */
+ if (who == INT_MIN)
+ return -EINVAL;
+
type = PIDTYPE_PGID;
who = -who;
}