Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=acd644bb4abb4d9f0ba6b9ec2b356263971ef9d0
Commit: acd644bb4abb4d9f0ba6b9ec2b356263971ef9d0
Parent: 1a8514e04e3f0249a75f66225e99cdf48d305be7
Author: H. Peter Anvin <[EMAIL PROTECTED]>
AuthorDate: Wed Jan 30 13:33:04 2008 +0100
Committer: Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Wed Jan 30 13:33:04 2008 +0100
x86 setup: guard the heap against invalid stack setups
If we use the bootloader-provided stack pointer, we might end up in a
situation where the bootloader (incorrectly) pointed the stack in the
middle of our heap. Catch this by simply comparing the computed heap
end value to the stack pointer minus the defined stack size.
Signed-off-by: H. Peter Anvin <[EMAIL PROTECTED]>
Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
---
arch/x86/boot/main.c | 24 ++++++++++++++++++------
1 files changed, 18 insertions(+), 6 deletions(-)
diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c
index 22ca62b..7828da5 100644
--- a/arch/x86/boot/main.c
+++ b/arch/x86/boot/main.c
@@ -100,20 +100,32 @@ static void set_bios_mode(void)
#endif
}
-void main(void)
+static void init_heap(void)
{
- /* First, copy the boot header into the "zeropage" */
- copy_boot_params();
+ char *stack_end;
- /* End of heap check */
if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
- heap_end = (char *)(boot_params.hdr.heap_end_ptr
- +0x200-STACK_SIZE);
+ asm("leal %P1(%%esp),%0"
+ : "=r" (stack_end) : "i" (-STACK_SIZE));
+
+ heap_end = (char *)
+ ((size_t)boot_params.hdr.heap_end_ptr + 0x200);
+ if (heap_end > stack_end)
+ heap_end = stack_end;
} else {
/* Boot protocol 2.00 only, no heap available */
puts("WARNING: Ancient bootloader, some functionality "
"may be limited!\n");
}
+}
+
+void main(void)
+{
+ /* First, copy the boot header into the "zeropage" */
+ copy_boot_params();
+
+ /* End of heap check */
+ init_heap();
/* Make sure we have all the proper CPU support */
if (validate_cpu()) {
-
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