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x86/kexec: Avoid double free_page() upon do_kexec_load() failure
commita466ef76b8
upstream. >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: 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:f5deb79679
("x86: kexec: Use one page table in x86_64 machine_kexec") Fixes:92be3d6bdf
("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 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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2 changed files with 9 additions and 2 deletions
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@ -57,12 +57,17 @@ static void load_segments(void)
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static void machine_kexec_free_page_tables(struct kimage *image)
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{
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free_page((unsigned long)image->arch.pgd);
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image->arch.pgd = NULL;
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#ifdef CONFIG_X86_PAE
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free_page((unsigned long)image->arch.pmd0);
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image->arch.pmd0 = NULL;
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free_page((unsigned long)image->arch.pmd1);
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image->arch.pmd1 = NULL;
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#endif
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free_page((unsigned long)image->arch.pte0);
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image->arch.pte0 = NULL;
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free_page((unsigned long)image->arch.pte1);
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image->arch.pte1 = NULL;
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}
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static int machine_kexec_alloc_page_tables(struct kimage *image)
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@ -79,7 +84,6 @@ static int machine_kexec_alloc_page_tables(struct kimage *image)
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!image->arch.pmd0 || !image->arch.pmd1 ||
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#endif
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!image->arch.pte0 || !image->arch.pte1) {
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machine_kexec_free_page_tables(image);
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return -ENOMEM;
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}
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return 0;
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@ -38,9 +38,13 @@ static struct kexec_file_ops *kexec_file_loaders[] = {
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static void free_transition_pgtable(struct kimage *image)
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{
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free_page((unsigned long)image->arch.p4d);
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image->arch.p4d = NULL;
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free_page((unsigned long)image->arch.pud);
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image->arch.pud = NULL;
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free_page((unsigned long)image->arch.pmd);
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image->arch.pmd = NULL;
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free_page((unsigned long)image->arch.pte);
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image->arch.pte = NULL;
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}
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static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
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@ -90,7 +94,6 @@ static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
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set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC_NOENC));
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return 0;
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err:
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free_transition_pgtable(image);
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return result;
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}
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