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| author | Tejun Heo <tj@kernel.org> | 2009-02-09 22:17:40 +0900 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-02-10 00:42:01 +0100 |
| commit | 60a5317ff0f42dd313094b88f809f63041568b08 (patch) | |
| tree | 307dfd9715fbc9ff83c3c3ae3b0e8f03888083f2 /arch/x86/kernel/process_32.c | |
| parent | ccbeed3a05908d201b47b6c3dd1a373138bba566 (diff) | |
| download | blackbird-op-linux-60a5317ff0f42dd313094b88f809f63041568b08.tar.gz blackbird-op-linux-60a5317ff0f42dd313094b88f809f63041568b08.zip | |
x86: implement x86_32 stack protector
Impact: stack protector for x86_32
Implement stack protector for x86_32. GDT entry 28 is used for it.
It's set to point to stack_canary-20 and have the length of 24 bytes.
CONFIG_CC_STACKPROTECTOR turns off CONFIG_X86_32_LAZY_GS and sets %gs
to the stack canary segment on entry. As %gs is otherwise unused by
the kernel, the canary can be anywhere. It's defined as a percpu
variable.
x86_32 exception handlers take register frame on stack directly as
struct pt_regs. With -fstack-protector turned on, gcc copies the
whole structure after the stack canary and (of course) doesn't copy
back on return thus losing all changed. For now, -fno-stack-protector
is added to all files which contain those functions. We definitely
need something better.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/process_32.c')
| -rw-r--r-- | arch/x86/kernel/process_32.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 86122fa2a1ba..9a62383e7c3c 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -212,6 +212,7 @@ int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) regs.ds = __USER_DS; regs.es = __USER_DS; regs.fs = __KERNEL_PERCPU; + regs.gs = __KERNEL_STACK_CANARY; regs.orig_ax = -1; regs.ip = (unsigned long) kernel_thread_helper; regs.cs = __KERNEL_CS | get_kernel_rpl(); |
