>From 91a78abed036e1662b11cb54ae6300864e17b709 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> Date: Fri, 4 May 2018 08:26:41 +0900 Subject: [PATCH v2] x86/kexec: avoid double free_page() upon do_kexec_load() failure.
syzbot is reporting crashes after memory allocation failure inside do_kexec_load() [1]. This is because free_transition_pgtable() is called by both init_transition_pgtable() and machine_kexec_cleanup() when memory allocation failed inside init_transition_pgtable(). Regarding 32bit code, machine_kexec_free_page_tables() is called by both machine_kexec_alloc_page_tables() and machine_kexec_cleanup() when memory allocation failed inside machine_kexec_alloc_page_tables(). Fix this by leaving the error handling to machine_kexec_cleanup(). [1] https://syzkaller.appspot.com/bug?id=91e52396168cf2bdd572fe1e1bc0bc645c1c6b40 Signed-off-by: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> Reported-by: syzbot <syzbot+d96f60296ef613fe1...@syzkaller.appspotmail.com> Fixes: f5deb79679af6eb4 ("x86: kexec: Use one page table in x86_64 machine_kexec") Fixes: 92be3d6bdf2cb349 ("kexec/i386: allocate page table pages dynamically") Cc: Huang Ying <ying.hu...@intel.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Ingo Molnar <mi...@elte.hu> --- arch/x86/kernel/machine_kexec_32.c | 1 - arch/x86/kernel/machine_kexec_64.c | 1 - 2 files changed, 2 deletions(-) diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c index 60cdec6..170fbf8 100644 --- a/arch/x86/kernel/machine_kexec_32.c +++ b/arch/x86/kernel/machine_kexec_32.c @@ -79,7 +79,6 @@ static int machine_kexec_alloc_page_tables(struct kimage *image) !image->arch.pmd0 || !image->arch.pmd1 || #endif !image->arch.pte0 || !image->arch.pte1) { - machine_kexec_free_page_tables(image); return -ENOMEM; } return 0; diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c index a5e55d8..ffe0174 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -91,7 +91,6 @@ static int init_transition_pgtable(struct kimage *image, pgd_t *pgd) set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC_NOENC)); return 0; err: - free_transition_pgtable(image); return result; } -- 1.8.3.1
