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| author | Jiang Biao <jiang.biao2@zte.com.cn> | 2018-07-20 08:06:32 +0800 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-07-20 07:07:39 +0200 |
| commit | 8c934e01a7ce685d98e970880f5941d79272c654 (patch) | |
| tree | 31d28a6c15860b60aecd2c30d1c0098c3b98ff13 /arch/x86/mm/pti.c | |
| parent | b2b7d986a89b6c94b1331a909de1217214fb08c1 (diff) | |
| download | linux-8c934e01a7ce685d98e970880f5941d79272c654.tar.bz2 | |
x86/pti: Check the return value of pti_user_pagetable_walk_pmd()
pti_user_pagetable_walk_pmd() can return NULL, so the return value should
be checked to prevent a NULL pointer dereference.
Add the check and a warning when the PMD 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/1532045192-49622-2-git-send-email-jiang.biao2@zte.com.cn
Diffstat (limited to 'arch/x86/mm/pti.c')
| -rw-r--r-- | arch/x86/mm/pti.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 001ee6b0619e..bcf35dac1920 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -205,7 +205,7 @@ static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address) BUILD_BUG_ON(p4d_large(*p4d) != 0); if (p4d_none(*p4d)) { unsigned long new_pud_page = __get_free_page(gfp); - if (!new_pud_page) + if (WARN_ON_ONCE(!new_pud_page)) return NULL; set_p4d(p4d, __p4d(_KERNPG_TABLE | __pa(new_pud_page))); @@ -219,7 +219,7 @@ static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address) } if (pud_none(*pud)) { unsigned long new_pmd_page = __get_free_page(gfp); - if (!new_pmd_page) + if (WARN_ON_ONCE(!new_pmd_page)) return NULL; set_pud(pud, __pud(_KERNPG_TABLE | __pa(new_pmd_page))); @@ -241,9 +241,13 @@ static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address) static __init pte_t *pti_user_pagetable_walk_pte(unsigned long address) { gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO); - pmd_t *pmd = pti_user_pagetable_walk_pmd(address); + pmd_t *pmd; pte_t *pte; + pmd = pti_user_pagetable_walk_pmd(address); + if (!pmd) + return NULL; + /* We can't do anything sensible if we hit a large mapping. */ if (pmd_large(*pmd)) { WARN_ON(1); |