[tip:core/urgent] futex: Take mmap_sem for get_user_pages in fault_in_user_writeable
From: tip-bot for Andi Kleen
Date: Tue Dec 08 2009 - 09:04:28 EST
Commit-ID: 722d0172377a5697919b9f7e5beb95165b1dec4e
Gitweb: http://git.kernel.org/tip/722d0172377a5697919b9f7e5beb95165b1dec4e
Author: Andi Kleen <andi@xxxxxxxxxxxxxx>
AuthorDate: Tue, 8 Dec 2009 13:19:42 +0100
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Tue, 8 Dec 2009 14:59:36 +0100
futex: Take mmap_sem for get_user_pages in fault_in_user_writeable
get_user_pages() must be called with mmap_sem held.
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxx
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxx>
Cc: Darren Hart <dvhltc@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
LKML-Reference: <20091208121942.GA21298@xxxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
kernel/futex.c | 10 ++++++++--
1 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index fb65e82..d73ef1f 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -304,8 +304,14 @@ void put_futex_key(int fshared, union futex_key *key)
*/
static int fault_in_user_writeable(u32 __user *uaddr)
{
- int ret = get_user_pages(current, current->mm, (unsigned long)uaddr,
- 1, 1, 0, NULL, NULL);
+ struct mm_struct *mm = current->mm;
+ int ret;
+
+ down_read(&mm->mmap_sem);
+ ret = get_user_pages(current, mm, (unsigned long)uaddr,
+ 1, 1, 0, NULL, NULL);
+ up_read(&mm->mmap_sem);
+
return ret < 0 ? ret : 0;
}
--
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