From: tip-bot for Chen Jie <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: mingo@kernel.org, linux-kernel@vger.kernel.org,
dvhart@infradead.org, hpa@zytor.com, tglx@linutronix.de,
peterz@infradead.org, chenjie6@huawei.com, zengweilin@huawei.com
Subject: [tip:locking/urgent] futex: Ensure that futex address is aligned in handle_futex_death()
Date: Fri, 22 Mar 2019 05:10:18 -0700 [thread overview]
Message-ID: <tip-5a07168d8d89b00fe1760120714378175b3ef992@git.kernel.org> (raw)
In-Reply-To: <1552621478-119787-1-git-send-email-chenjie6@huawei.com>
Commit-ID: 5a07168d8d89b00fe1760120714378175b3ef992
Gitweb: https://git.kernel.org/tip/5a07168d8d89b00fe1760120714378175b3ef992
Author: Chen Jie <chenjie6@huawei.com>
AuthorDate: Fri, 15 Mar 2019 03:44:38 +0000
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 22 Mar 2019 13:05:26 +0100
futex: Ensure that futex address is aligned in handle_futex_death()
The futex code requires that the user space addresses of futexes are 32bit
aligned. sys_futex() checks this in futex_get_keys() but the robust list
code has no alignment check in place.
As a consequence the kernel crashes on architectures with strict alignment
requirements in handle_futex_death() when trying to cmpxchg() on an
unaligned futex address which was retrieved from the robust list.
[ tglx: Rewrote changelog, proper sizeof() based alignement check and add
comment ]
Fixes: 0771dfefc9e5 ("[PATCH] lightweight robust futexes: core")
Signed-off-by: Chen Jie <chenjie6@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <dvhart@infradead.org>
Cc: <peterz@infradead.org>
Cc: <zengweilin@huawei.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1552621478-119787-1-git-send-email-chenjie6@huawei.com
---
kernel/futex.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/futex.c b/kernel/futex.c
index c3b73b0311bc..9e40cf7be606 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3436,6 +3436,10 @@ static int handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int p
{
u32 uval, uninitialized_var(nval), mval;
+ /* Futex address must be 32bit aligned */
+ if ((((unsigned long)uaddr) % sizeof(*uaddr)) != 0)
+ return -1;
+
retry:
if (get_user(uval, uaddr))
return -1;
prev parent reply other threads:[~2019-03-22 12:36 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-15 3:44 [PATCH] futex:fix robust futex alignment exception chenjie6
2019-03-15 8:41 ` Peter Zijlstra
2019-03-17 14:36 ` Thomas Gleixner
2019-03-18 10:48 ` Peter Zijlstra
2019-03-18 11:35 ` Chenjie (K)
2019-03-22 12:10 ` tip-bot for Chen Jie [this message]
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