4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> commit a466ef76b815b86748d9870ef2a430af7b39c710 upstream. >From ff82bedd3e12f0d3353282054ae48c3bd8c72012 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Date: Wed, 9 May 2018 12:12:39 +0900 Subject: [PATCH 4.9 23/96] 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() (and optionally setting NULL after free_page()). [1] https://syzkaller.appspot.com/bug?id=91e52396168cf2bdd572fe1e1bc0bc645c1c6b40 Fixes: f5deb79679af6eb4 ("x86: kexec: Use one page table in x86_64 machine_kexec") Fixes: 92be3d6bdf2cb349 ("kexec/i386: allocate page table pages dynamically") Reported-by: syzbot <syzbot+d96f60296ef613fe1d69@xxxxxxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Acked-by: Baoquan He <bhe@xxxxxxxxxx> Cc: thomas.lendacky@xxxxxxx Cc: prudo@xxxxxxxxxxxxxxxxxx Cc: Huang Ying <ying.huang@xxxxxxxxx> Cc: syzkaller-bugs@xxxxxxxxxxxxxxxx Cc: takahiro.akashi@xxxxxxxxxx Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: akpm@xxxxxxxxxxxxxxxxxxxx Cc: dyoung@xxxxxxxxxx Cc: kirill.shutemov@xxxxxxxxxxxxxxx Link: https://lkml.kernel.org/r/201805091942.DGG12448.tMFVFSJFQOOLHO@xxxxxxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/machine_kexec_32.c | 6 +++++- arch/x86/kernel/machine_kexec_64.c | 4 +++- 2 files changed, 8 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/machine_kexec_32.c +++ b/arch/x86/kernel/machine_kexec_32.c @@ -71,12 +71,17 @@ static void load_segments(void) static void machine_kexec_free_page_tables(struct kimage *image) { free_page((unsigned long)image->arch.pgd); + image->arch.pgd = NULL; #ifdef CONFIG_X86_PAE free_page((unsigned long)image->arch.pmd0); + image->arch.pmd0 = NULL; free_page((unsigned long)image->arch.pmd1); + image->arch.pmd1 = NULL; #endif free_page((unsigned long)image->arch.pte0); + image->arch.pte0 = NULL; free_page((unsigned long)image->arch.pte1); + image->arch.pte1 = NULL; } static int machine_kexec_alloc_page_tables(struct kimage *image) @@ -93,7 +98,6 @@ static int machine_kexec_alloc_page_tabl !image->arch.pmd0 || !image->arch.pmd1 || #endif !image->arch.pte0 || !image->arch.pte1) { - machine_kexec_free_page_tables(image); return -ENOMEM; } return 0; --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -37,8 +37,11 @@ static struct kexec_file_ops *kexec_file static void free_transition_pgtable(struct kimage *image) { free_page((unsigned long)image->arch.pud); + image->arch.pud = NULL; free_page((unsigned long)image->arch.pmd); + image->arch.pmd = NULL; free_page((unsigned long)image->arch.pte); + image->arch.pte = NULL; } static int init_transition_pgtable(struct kimage *image, pgd_t *pgd) @@ -79,7 +82,6 @@ static int init_transition_pgtable(struc set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC)); return 0; err: - free_transition_pgtable(image); return result; }
