From: Andi Kleen <ak@suse.de>
Date: Tue, 17 May 2005 04:53:30 +0000 (-0700)
Subject: [PATCH] x86_64: Fix canonical checking for segment registers in ptrace
X-Git-Tag: v2.6.12-rc5~143
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f6b8d4778c04148729cc0b0dcd335a4411c44276;p=linux-2.6

[PATCH] x86_64: Fix canonical checking for segment registers in ptrace

Allowed user programs to set a non canonical segment base, which would cause
oopses in the kernel later.

Credit-to: Alexander Nyberg <alexn@dsv.su.se>

 For identifying and reporting this bug.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/arch/x86_64/kernel/ptrace.c b/arch/x86_64/kernel/ptrace.c
index 892212161a..60dc9b9895 100644
--- a/arch/x86_64/kernel/ptrace.c
+++ b/arch/x86_64/kernel/ptrace.c
@@ -257,13 +257,13 @@ static int putreg(struct task_struct *child,
 			value &= 0xffff;
 			return 0;
 		case offsetof(struct user_regs_struct,fs_base):
-			if (!((value >> 48) == 0 || (value >> 48) == 0xffff))
-				return -EIO; 
+			if (value >= TASK_SIZE)
+				return -EIO;
 			child->thread.fs = value;
 			return 0;
 		case offsetof(struct user_regs_struct,gs_base):
-			if (!((value >> 48) == 0 || (value >> 48) == 0xffff))
-				return -EIO; 
+			if (value >= TASK_SIZE)
+				return -EIO;
 			child->thread.gs = value;
 			return 0;
 		case offsetof(struct user_regs_struct, eflags):