[ Upstream commit 2cd4bd192ee94848695c1c052d87913260e10f36 ]
Protection key tracking information is not copied over to the mm_struct of the child during fork(). This can cause the child to erroneously allocate keys that were already allocated. Any allocated execute-only key is lost aswell.
Add code; called by dup_mmap(), to copy the pkey state from parent to child explicitly.
This problem was originally found by Dave Hansen on x86, which turns out to be a problem on powerpc aswell.
Fixes: cf43d3b26452 ("powerpc: Enable pkey subsystem") Cc: stable@vger.kernel.org # v4.16+ Reviewed-by: Thiago Jung Bauermann bauerman@linux.ibm.com Signed-off-by: Ram Pai linuxram@us.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/include/asm/mmu_context.h | 15 +++++++++------ arch/powerpc/mm/pkeys.c | 10 ++++++++++ 2 files changed, 19 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h index b694d6af11508..ae953958c0f33 100644 --- a/arch/powerpc/include/asm/mmu_context.h +++ b/arch/powerpc/include/asm/mmu_context.h @@ -217,12 +217,6 @@ static inline void enter_lazy_tlb(struct mm_struct *mm, #endif }
-static inline int arch_dup_mmap(struct mm_struct *oldmm, - struct mm_struct *mm) -{ - return 0; -} - #ifndef CONFIG_PPC_BOOK3S_64 static inline void arch_exit_mmap(struct mm_struct *mm) { @@ -247,6 +241,7 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm, #ifdef CONFIG_PPC_MEM_KEYS bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write, bool execute, bool foreign); +void arch_dup_pkeys(struct mm_struct *oldmm, struct mm_struct *mm); #else /* CONFIG_PPC_MEM_KEYS */ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write, bool execute, bool foreign) @@ -259,6 +254,7 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma, #define thread_pkey_regs_save(thread) #define thread_pkey_regs_restore(new_thread, old_thread) #define thread_pkey_regs_init(thread) +#define arch_dup_pkeys(oldmm, mm)
static inline u64 pte_to_hpte_pkey_bits(u64 pteflags) { @@ -267,5 +263,12 @@ static inline u64 pte_to_hpte_pkey_bits(u64 pteflags)
#endif /* CONFIG_PPC_MEM_KEYS */
+static inline int arch_dup_mmap(struct mm_struct *oldmm, + struct mm_struct *mm) +{ + arch_dup_pkeys(oldmm, mm); + return 0; +} + #endif /* __KERNEL__ */ #endif /* __ASM_POWERPC_MMU_CONTEXT_H */ diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c index b271b283c785e..25a8dd9cd71db 100644 --- a/arch/powerpc/mm/pkeys.c +++ b/arch/powerpc/mm/pkeys.c @@ -414,3 +414,13 @@ bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write,
return pkey_access_permitted(vma_pkey(vma), write, execute); } + +void arch_dup_pkeys(struct mm_struct *oldmm, struct mm_struct *mm) +{ + if (static_branch_likely(&pkey_disabled)) + return; + + /* Duplicate the oldmm pkey state in mm: */ + mm_pkey_allocation_map(mm) = mm_pkey_allocation_map(oldmm); + mm->context.execute_only_pkey = oldmm->context.execute_only_pkey; +}