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authorJiri Slaby <jslaby@suse.cz>2017-11-30 15:35:44 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2017-12-10 12:50:57 -0800
commitd70ef22892ed6c066e51e118b225923c9b74af34 (patch)
tree8a650ea3b1fe83e418607e5c8c40f7ec24e1eef8
parent51090c5d6de08cfc86b2d861775dedddd9a2c023 (diff)
downloadlinux-d70ef22892ed6c066e51e118b225923c9b74af34.tar.bz2
futex: futex_wake_op, fix sign_extend32 sign bits
sign_extend32 counts the sign bit parameter from 0, not from 1. So we have to use "11" for 12th bit, not "12". This mistake means we have not allowed negative op and cmp args since commit 30d6e0a4190d ("futex: Remove duplicated code and fix undefined behaviour") till now. Fixes: 30d6e0a4190d ("futex: Remove duplicated code and fix undefined behaviour") Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Darren Hart <dvhart@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/futex.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 76ed5921117a..57d0b3657e16 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1582,8 +1582,8 @@ static int futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *uaddr)
{
unsigned int op = (encoded_op & 0x70000000) >> 28;
unsigned int cmp = (encoded_op & 0x0f000000) >> 24;
- int oparg = sign_extend32((encoded_op & 0x00fff000) >> 12, 12);
- int cmparg = sign_extend32(encoded_op & 0x00000fff, 12);
+ int oparg = sign_extend32((encoded_op & 0x00fff000) >> 12, 11);
+ int cmparg = sign_extend32(encoded_op & 0x00000fff, 11);
int oldval, ret;
if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) {