[PATCH] arm64: fix strnlen_user when count <= strlen
From: Kyle McMartin <hidden>
Date: 2014-01-17 16:23:25
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On Fri, Jan 17, 2014 at 10:51:07AM +0000, Will Deacon wrote:
Actually, I have removed strnlen_user for 3.14. Could you try your test case with our for-next branch please? git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
This will work fine, I believe (I can't easily test on HW since we're dependent on $vendor drivers that aren't upstream yet) but in my testing yesterday I parroted the x86 word-at-a-time.h and lib/strnlen_user.c and that seemed to work.
As for the issue you spotted, we probably need a fix for that to go into stable kernels. Does the following (smaller patch) work for you?
This gets the count == 0 case wrong still, I believe. === count = 0 === strnlen_user = 0 __strnlen_user = 1 (Where strnlen_user is the lib/strnlen_user.c implementation.) Testing if (n <= 0) return 0; before __strnlen_user fixes it though. Given this is called in, I think, only two places in the kernel, maybe we should just backport the switch to generic for stable? I can't imagine it conflicting with anything. regards, Kyle
quoted hunk ↗ jump to hunk
Will --->8diff --git a/arch/arm64/lib/strnlen_user.S b/arch/arm64/lib/strnlen_user.S index 7f7b176a5646..73f3335a2a45 100644 --- a/arch/arm64/lib/strnlen_user.S +++ b/arch/arm64/lib/strnlen_user.S@@ -37,6 +37,7 @@ ENTRY(__strnlen_user) USER(9f, ldrb w3, [x0], #1 ) cbnz w3, 1b 2: sub x0, x0, x2 + cinc x0, x0, mi ret ENDPROC(__strnlen_user)