[patch 13/16] x86_64: Fix canonical checking for segment registers in ptrace

Chris Wright
2005-05-23T23:45:08Z

[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>
Signed-off-by: Chris Wright <chrisw@osdl.org>
---

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

Index: release-2.6.11/arch/x86_64/kernel/ptrace.c
===================================================================
--- release-2.6.11.orig/arch/x86_64/kernel/ptrace.c
+++ release-2.6.11/arch/x86_64/kernel/ptrace.c
@@ -129,13 +129,13 @@ static int putreg(struct task_struct *ch
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):