| From 56b88a3bf97a39d3f4f010509917b76a865a6dc8 Mon Sep 17 00:00:00 2001 |
| From: Richard Weinberger <richard@nod.at> |
| Date: Sun, 9 Aug 2015 22:26:33 +0200 |
| Subject: um: Fix kernel mode fault condition |
| |
| From: Richard Weinberger <richard@nod.at> |
| |
| commit 56b88a3bf97a39d3f4f010509917b76a865a6dc8 upstream. |
| |
| We have to exclude memory locations <= PAGE_SIZE from |
| the condition and let the kernel mode fault path catch it. |
| Otherwise a kernel NULL pointer exception will be reported |
| as a kernel user space access. |
| |
| Fixes: d2313084e2c (um: Catch unprotected user memory access) |
| Signed-off-by: Richard Weinberger <richard@nod.at> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/um/kernel/trap.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/arch/um/kernel/trap.c |
| +++ b/arch/um/kernel/trap.c |
| @@ -220,7 +220,7 @@ unsigned long segv(struct faultinfo fi, |
| show_regs(container_of(regs, struct pt_regs, regs)); |
| panic("Segfault with no mm"); |
| } |
| - else if (!is_user && address < TASK_SIZE) { |
| + else if (!is_user && address > PAGE_SIZE && address < TASK_SIZE) { |
| show_regs(container_of(regs, struct pt_regs, regs)); |
| panic("Kernel tried to access user memory at addr 0x%lx, ip 0x%lx", |
| address, ip); |
