linux-kernel - [60/75] net: bpf_jit: fix an off-one bug in x86

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 03 Jan 2012 14:33:33 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk,
	Markus Kötter <nepenthesdev@...il.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [60/75] net: bpf_jit: fix an off-one bug in x86_64 cond jump target

3.1-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Markus Kötter <nepenthesdev@...il.com>

[ Upstream commit a03ffcf873fe0f2565386ca8ef832144c42e67fa ]

x86 jump instruction size is 2 or 5 bytes (near/long jump), not 2 or 6
bytes.

In case a conditional jump is followed by a long jump, conditional jump
target is one byte past the start of target instruction.

Signed-off-by: Markus Kötter <nepenthesdev@...il.com>
Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 arch/x86/net/bpf_jit_comp.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -568,8 +568,8 @@ cond_branch:			f_offset = addrs[i + filt
 					break;
 				}
 				if (filter[i].jt != 0) {
-					if (filter[i].jf)
-						t_offset += is_near(f_offset) ? 2 : 6;
+					if (filter[i].jf && f_offset)
+						t_offset += is_near(f_offset) ? 2 : 5;
 					EMIT_COND_JMP(t_op, t_offset);
 					if (filter[i].jf)
 						EMIT_JMP(f_offset);


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/