[PATCH 1/1] kgdb,i386: Fix corner case access to sp with NMI watch dog exception

[Jason Wessel]

It is possible for the user_mode_vm(regs) check to return true for a
non master kgdb cpu or when the master kgdb cpu handles the NMI watch
dog exception.

The solution is simply to select the correct stack pointer location
based on the check to user_mode_vm(regs).

Signed-off-by: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>

---
 arch/x86/kernel/kgdb.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -85,10 +85,15 @@ void pt_regs_to_gdb_regs(unsigned long *
 	gdb_regs[GDB_DS]	= regs->ds;
 	gdb_regs[GDB_ES]	= regs->es;
 	gdb_regs[GDB_CS]	= regs->cs;
-	gdb_regs[GDB_SS]	= __KERNEL_DS;
 	gdb_regs[GDB_FS]	= 0xFFFF;
 	gdb_regs[GDB_GS]	= 0xFFFF;
-	gdb_regs[GDB_SP]	= (int)&regs->sp;
+	if (user_mode_vm(regs)) {
+		gdb_regs[GDB_SS] = regs->ss;
+		gdb_regs[GDB_SP] = regs->sp;
+	} else {
+		gdb_regs[GDB_SS] = __KERNEL_DS;
+		gdb_regs[GDB_SP] = (unsigned long)&regs->sp;
+	}
 #else
 	gdb_regs[GDB_R8]	= regs->r8;
 	gdb_regs[GDB_R9]	= regs->r9;

--------------030303010503030205090903--
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/