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| author | Jiang Biao <jiang.biao2@zte.com.cn> | 2018-07-20 02:06:31 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-07-20 07:07:39 +0200 |
| commit | b2b7d986a89b6c94b1331a909de1217214fb08c1 (patch) | |
| tree | 9cce6d8e6a0860e7476f3b57172ded3e8159826b /arch/x86/mm | |
| parent | x86/entry/32: Add debug code to check entry/exit CR3 (diff) | |
| download | linux-b2b7d986a89b6c94b1331a909de1217214fb08c1.tar.xz linux-b2b7d986a89b6c94b1331a909de1217214fb08c1.zip | |
x86/pti: Check the return value of pti_user_pagetable_walk_p4d()
pti_user_pagetable_walk_p4d() can return NULL, so the return value should
be checked to prevent a NULL pointer dereference.
Add the check and a warning when the P4D allocation fails.
Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: dave.hansen@linux.intel.com
Cc: luto@kernel.org
Cc: hpa@zytor.com
Cc: albcamus@gmail.com
Cc: zhong.weidong@zte.com.cn
Link: https://lkml.kernel.org/r/1532045192-49622-1-git-send-email-jiang.biao2@zte.com.cn
Diffstat (limited to 'arch/x86/mm')
| -rw-r--r-- | arch/x86/mm/pti.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 7b1c85759005..001ee6b0619e 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -176,7 +176,7 @@ static p4d_t *pti_user_pagetable_walk_p4d(unsigned long address) if (pgd_none(*pgd)) { unsigned long new_p4d_page = __get_free_page(gfp); - if (!new_p4d_page) + if (WARN_ON_ONCE(!new_p4d_page)) return NULL; set_pgd(pgd, __pgd(_KERNPG_TABLE | __pa(new_p4d_page))); @@ -195,9 +195,13 @@ static p4d_t *pti_user_pagetable_walk_p4d(unsigned long address) static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address) { gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO); - p4d_t *p4d = pti_user_pagetable_walk_p4d(address); + p4d_t *p4d; pud_t *pud; + p4d = pti_user_pagetable_walk_p4d(address); + if (!p4d) + return NULL; + BUILD_BUG_ON(p4d_large(*p4d) != 0); if (p4d_none(*p4d)) { unsigned long new_pud_page = __get_free_page(gfp); @@ -359,6 +363,9 @@ static void __init pti_clone_p4d(unsigned long addr) pgd_t *kernel_pgd; user_p4d = pti_user_pagetable_walk_p4d(addr); + if (!user_p4d) + return; + kernel_pgd = pgd_offset_k(addr); kernel_p4d = p4d_offset(kernel_pgd, addr); *user_p4d = *kernel_p4d; |