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Patch "arm64: bpf: fix signedness bug in loading 64-bit immediate" has been added to the 4.0-stable tree

PATCH [email protected] 1 participant 1 message Jun 3, 2015

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Stable branch BPF arm64 BPF JIT for arm64
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This is a note to let you know that I've just added the patch titled

arm64: bpf: fix signedness bug in loading 64-bit immediate

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm64-bpf-fix-signedness-bug-in-loading-64-bit-immediate.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 1e4df6b7208140f3c49f316d33a409d3a161f350 Mon Sep 17 00:00:00 2001

From: Xi Wang <[email protected]>
Date: Fri, 8 May 2015 06:39:51 +0100
Subject: arm64: bpf: fix signedness bug in loading 64-bit immediate

From: Xi Wang <[email protected]>

commit 1e4df6b7208140f3c49f316d33a409d3a161f350 upstream.

Consider "(u64)insn1.imm << 32 | imm" in the arm64 JIT. Since imm is signed 32-bit, it is sign-extended to 64-bit, losing the high 32 bits. The fix is to convert imm to u32 first, which will be zero-extended to u64 implicitly.

Cc Zi Shen Lim <[email protected]>
Cc Alexei Starovoitov <[email protected]>
Cc Catalin Marinas <[email protected]>
Fixes 30d3d94cc3d5 ("arm64: bpf: add 'load 64-bit immediate' instruction")
Signed-off-by Xi Wang <[email protected]>
[will: removed non-arm64 bits and redundant casting]
Signed-off-by Will Deacon <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 arch/arm64/net/bpf_jit_comp.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/arm64/net/bpf_jit_comp.c +1 -1
@@ -487,7 +487,7 @@ emit_cond_jmp:
 			return -EINVAL;
 		}
 
-		imm64 = (u64)insn1.imm << 32 | imm;
+		imm64 = (u64)insn1.imm << 32 | (u32)imm;
 		emit_a64_mov_i64(dst, imm64, ctx);
 
 		return 1;

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/arm64-bpf-fix-signedness-bug-in-loading-64-bit-immediate.patch