This is a note to let you know that I've just added the patch titled
fs/fcntl: f_setown, avoid undefined behaviour
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fs-fcntl-f_setown-avoid-undefined-behaviour.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From fc3dc67471461c0efcb1ed22fb7595121d65fad9 Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@xxxxxxx>
Date: Tue, 13 Jun 2017 13:35:51 +0200
Subject: fs/fcntl: f_setown, avoid undefined behaviour
From: Jiri Slaby <jslaby@xxxxxxx>
commit fc3dc67471461c0efcb1ed22fb7595121d65fad9 upstream.
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@xxxxxxx>
Cc: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
Cc: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/fcntl.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -113,6 +113,10 @@ void f_setown(struct file *filp, unsigne
int who = arg;
type = PIDTYPE_PID;
if (who < 0) {
+ /* avoid overflow below */
+ if (who == INT_MIN)
+ return;
+
type = PIDTYPE_PGID;
who = -who;
}
Patches currently in stable-queue which might be from jslaby@xxxxxxx are
queue-4.4/ipc-msg-make-msgrcv-work-with-long_min.patch
queue-4.4/fs-fcntl-f_setown-avoid-undefined-behaviour.patch
queue-4.4/pm-sleep-declare-__tracedata-symbols-as-char-rather-than-char.patch
queue-4.4/x86-cpu-intel-introduce-macros-for-intel-family-numbers.patch
queue-4.4/x86-retpoline-fill-rsb-on-context-switch-for-affected-cpus.patch
queue-4.4/acpi-scan-prefer-devices-without-_hid-_cid-for-_adr-matching.patch
queue-4.4/time-avoid-undefined-behaviour-in-ktime_add_safe.patch