futex: futex_wake_op, fix sign_extend32 sign bits
commit d70ef22892ed6c066e51e118b225923c9b74af34 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/kernel/futex.c b/kernel/futex.c
index 401d99a..c3ea6f2 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1462,8 +1462,8 @@
{
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)) {