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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2018-05-09 13:42:20 +0300
committerThomas Gleixner <tglx@linutronix.de>2018-05-13 20:50:06 +0300
commita466ef76b815b86748d9870ef2a430af7b39c710 (patch)
tree04a737c6be5691494571ee2fa66a65627ee77a93
parentccda3c4b77777f66aeb3c531352bb40d59501c59 (diff)
downloadlinux-a466ef76b815b86748d9870ef2a430af7b39c710.tar.xz
x86/kexec: Avoid double free_page() upon do_kexec_load() failure
>From ff82bedd3e12f0d3353282054ae48c3bd8c72012 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Date: Wed, 9 May 2018 12:12:39 +0900 Subject: [PATCH v3] 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@syzkaller.appspotmail.com> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Baoquan He <bhe@redhat.com> Cc: thomas.lendacky@amd.com Cc: prudo@linux.vnet.ibm.com Cc: Huang Ying <ying.huang@intel.com> Cc: syzkaller-bugs@googlegroups.com Cc: takahiro.akashi@linaro.org Cc: H. Peter Anvin <hpa@zytor.com> Cc: akpm@linux-foundation.org Cc: dyoung@redhat.com Cc: kirill.shutemov@linux.intel.com Link: https://lkml.kernel.org/r/201805091942.DGG12448.tMFVFSJFQOOLHO@I-love.SAKURA.ne.jp
-rw-r--r--arch/x86/kernel/machine_kexec_32.c6
-rw-r--r--arch/x86/kernel/machine_kexec_64.c5
2 files changed, 9 insertions, 2 deletions
diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c
index 60cdec6628b0..d1ab07ec8c9a 100644
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -57,12 +57,17 @@ 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)
@@ -79,7 +84,6 @@ 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 a5e55d832d0a..6010449ca6d2 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -39,9 +39,13 @@ const struct kexec_file_ops * const kexec_file_loaders[] = {
static void free_transition_pgtable(struct kimage *image)
{
free_page((unsigned long)image->arch.p4d);
+ image->arch.p4d = NULL;
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)
@@ -91,7 +95,6 @@ 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;
}