Messages in this thread Patch in this message | | | Date | Thu, 31 Jul 2014 20:05:20 -0700 | From | Omar Sandoval <> | Subject | [PATCH] ARM: don't enter kgdb when userspace executes a kgdb break instruction. |
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The kgdb breakpoint hooks (kgdb_brk_fn and kgdb_compiled_brk_fn) should only be entered when a kgdb break instruction is executed from the kernel. Otherwise, if kgdb is enabled, a userspace program can cause the kernel to drop into the debugger by executing either KGDB_BREAKINST or KGDB_COMPILED_BREAK.
Signed-off-by: Omar Sandoval <osandov@osandov.com> --- On a kernel running with kgdb enabled, this program reproduces the problem: .globl _start _start: udf #65006 @ KGDB_BREAKINST
The same problem has been fixed in ARM64.
arch/arm/kernel/kgdb.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c index 778c2f7..a74b53c 100644 --- a/arch/arm/kernel/kgdb.c +++ b/arch/arm/kernel/kgdb.c @@ -160,12 +160,16 @@ static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int instr) static struct undef_hook kgdb_brkpt_hook = { .instr_mask = 0xffffffff, .instr_val = KGDB_BREAKINST, + .cpsr_mask = MODE_MASK, + .cpsr_val = SVC_MODE, .fn = kgdb_brk_fn }; static struct undef_hook kgdb_compiled_brkpt_hook = { .instr_mask = 0xffffffff, .instr_val = KGDB_COMPILED_BREAK, + .cpsr_mask = MODE_MASK, + .cpsr_val = SVC_MODE, .fn = kgdb_compiled_brk_fn }; -- 2.0.3
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