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powerpc/32s: Fix bad_kuap_fault()

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At the moment, bad_kuap_fault() reports a fault only if a bad access
to userspace occurred while access to userspace was not granted.

But if a fault occurs for a write outside the allowed userspace
segment(s) that have been unlocked, bad_kuap_fault() fails to
detect it and the kernel loops forever in do_page_fault().

Fix it by checking that the accessed address is within the allowed
range.

Fixes: a68c31fc01 ("powerpc/32s: Implement Kernel Userspace Access Protection")
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f48244e9485ada0a304ed33ccbb8da271180c80d.1579866752.git.christophe.leroy@c-s.fr
This commit is contained in:
Christophe Leroy
2020-01-24 11:54:40 +00:00
committed by Michael Ellerman
parent 3c2659bd1d
commit 6ec20aa2e5
5 changed files with 17 additions and 6 deletions
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2
arch/powerpc/mm/fault.c
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@@ -233,7 +233,7 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code,
// Read/write fault in a valid region (the exception table search passed
// above), but blocked by KUAP is bad, it can never succeed.
if (bad_kuap_fault(regs, is_write))
if (bad_kuap_fault(regs, address, is_write))
return true;
// What's left? Kernel fault on user in well defined regions (extable