Commit-ID: 8f3365e34f7519904d78d9fb6dd9e4bae606b9b5
Gitweb: https://git.kernel.org/tip/8f3365e34f7519904d78d9fb6dd9e4bae606b9b5
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 6 Dec 2017 22:40:08 +0100
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Thu, 28 Dec 2017 15:19:12 +0100
futex: Sanitize user address in set_robust_list()
Passing in unaligned variables messes up cmpxchg on a whole bunch of
architectures and causes a in kernel lockup when the robust list is
accessed. Also, not respecting the natural alignment of data structures is
pretty dumb to begin with.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: dvhart@xxxxxxxxxxxxx
Cc: xiexiuqi@xxxxxxxxxx
Cc: Cheng Jian <cj.chengjian@xxxxxxxxxx>
Cc: huawei.libin@xxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20171206214007.GI3857@worktop
---
include/uapi/asm-generic/errno.h | 1 +
kernel/futex.c | 5 +++++
2 files changed, 6 insertions(+)
diff --git a/include/uapi/asm-generic/errno.h b/include/uapi/asm-generic/errno.h
index cf9c51a..e306ee4 100644
--- a/include/uapi/asm-generic/errno.h
+++ b/include/uapi/asm-generic/errno.h
@@ -119,5 +119,6 @@
#define ERFKILL 132 /* Operation not possible due to RF-kill */
#define EHWPOISON 133 /* Memory page has hardware error */
+#define EMORON 134 /* User did something particularly silly */
#endif
diff --git a/kernel/futex.c b/kernel/futex.c
index 57d0b36..4f471aa 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3262,6 +3262,8 @@ out:
SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head,
size_t, len)
{
+ unsigned long address = (unsigned long)head;
+
if (!futex_cmpxchg_enabled)
return -ENOSYS;
/*
@@ -3270,6 +3272,9 @@ SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head,
if (unlikely(len != sizeof(*head)))
return -EINVAL;
+ if (unlikely(address % __alignof__(*head)))
+ return -EMORON;
+
current->robust_list = head;
return 0;
--
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