9d92be1a09fbb3dd65600dbfe7eedb40e7228e4b

[ Upstream commit 3d8dcf278b1ee1eff1e90be848fa2237db4c07a7 ]
free_watch() does everything barring actually freeing the watch object. Fix
this by adding the missing kfree.
kmemleak produces a report something like the following. Note that as an
address can be seen in the first word, the watch would appear to have gone
through call_rcu().
BUG: memory leak
unreferenced object 0xffff88810ce4a200 (size 96):
comm "syz-executor352", pid 3605, jiffies 4294947473 (age 13.720s)
hex dump (first 32 bytes):
e0 82 48 0d 81 88 ff ff 00 00 00 00 00 00 00 00 ..H.............
80 a2 e4 0c 81 88 ff ff 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffffff8214e6cc>] kmalloc include/linux/slab.h:581 [inline]
[<ffffffff8214e6cc>] kzalloc include/linux/slab.h:714 [inline]
[<ffffffff8214e6cc>] keyctl_watch_key+0xec/0x2e0 security/keys/keyctl.c:1800
[<ffffffff8214ec84>] __do_sys_keyctl+0x3c4/0x490 security/keys/keyctl.c:2016
[<ffffffff84493a25>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<ffffffff84493a25>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
[<ffffffff84600068>] entry_SYSCALL_64_after_hwframe+0x44/0xae
Fixes: c73be61ced
("pipe: Add general notification queue support")
Reported-and-tested-by: syzbot+6e2de48f06cdb2884bfc@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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