| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.2 099/110] um: Fix kernel mode fault condition | Date | Fri, 6 Nov 2015 11:19:46 -0800 |
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4.2-stable review patch. If anyone has any objections, please let me know.
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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);
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