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| author | Jiri Slaby <jslaby@suse.cz> | 2017-11-30 15:35:44 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-12-10 12:50:57 -0800 |
| commit | d70ef22892ed6c066e51e118b225923c9b74af34 (patch) | |
| tree | 8a650ea3b1fe83e418607e5c8c40f7ec24e1eef8 /kernel/futex.c | |
| parent | 51090c5d6de08cfc86b2d861775dedddd9a2c023 (diff) | |
| download | lwn-d70ef22892ed6c066e51e118b225923c9b74af34.tar.gz lwn-d70ef22892ed6c066e51e118b225923c9b74af34.zip | |
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>
Diffstat (limited to 'kernel/futex.c')
| -rw-r--r-- | kernel/futex.c | 4 |
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)) { |