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Commit 9ba4ace3 authored by Segher Boessenkool's avatar Segher Boessenkool Committed by Paul Mackerras
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[POWERPC] PowerPC: Prevent data exception in kernel space (32-bit) 



The "is_exec" branch of the protection check in do_page_fault()
didn't do anything on 32-bit PowerPC.  So if a userland program
jumps to a page with Linux protection flags "---p", all the tests
happily fall through, and handle_mm_fault() is called, which in
turn calls handle_pte_fault(), which calls update_mmu_cache(),
which goes flush the dcache to a page with no access rights.

Boom.

This fixes it.

Signed-off-by: default avatarSegher Boessenkool <segher@kernel.crashing.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 7c8545e9

arch/powerpc/mm/fault.c

+2 −3
Original line number Diff line number Diff line
@@ -279,14 +279,13 @@ good_area: 
#endif /* CONFIG_8xx */



	if (is_exec) {

#ifdef CONFIG_PPC64

#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))

		/* protection fault */

		if (error_code & DSISR_PROTFAULT)

			goto bad_area;

		if (!(vma->vm_flags & VM_EXEC))

			goto bad_area;

#endif

#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)

#else

		pte_t *ptep;

		pmd_t *pmdp;