[PATCH] Fix canonical checking for segment registers in ptrace

tree f6097f56ad699f67e1c0dca233a095ce32715bc8
parent 2e7fe37125e00cf9090416345e36af80d7761e9a
author Andi Kleen <[email protected]> Tue, 28 Jun 2005 15:18:17 +0200
committer Marcelo Tosatti <[email protected]> Wed, 29 Jun 2005 16:50:00 -0300

[PATCH] Fix canonical checking for segment registers in ptrace

Fix canonical checking for segment registers in ptrace

This avoids a local DOS where a process could oops the kernel by
passing bogus values to ptrace. Some versions of UML did this.

Found by Alexander Nyberg

Signed-off-by: Andi Kleen <[email protected]>

 arch/x86_64/kernel/ptrace.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86_64/kernel/ptrace.c b/arch/x86_64/kernel/ptrace.c
--- a/arch/x86_64/kernel/ptrace.c
+++ b/arch/x86_64/kernel/ptrace.c
@@ -114,13 +114,13 @@ static int putreg(struct task_struct *ch
 			child->thread.es = 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):