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%3Ba=su...
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@vger.kernel.org know about it.
From fc3dc67471461c0efcb1ed22fb7595121d65fad9 Mon Sep 17 00:00:00 2001
From: Jiri Slaby jslaby@suse.cz Date: Tue, 13 Jun 2017 13:35:51 +0200 Subject: fs/fcntl: f_setown, avoid undefined behaviour
From: Jiri Slaby jslaby@suse.cz
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@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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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@suse.cz 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