From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: bhe@redhat.com, ying.huang@intel.com, hpa@zytor.com, mingo@elte.hu
Cc: syzbot+d96f60296ef613fe1d69@syzkaller.appspotmail.com,
kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com, akpm@linux-foundation.org,
dyoung@redhat.com, mingo@redhat.com, prudo@linux.vnet.ibm.com,
takahiro.akashi@linaro.org, tglx@linutronix.de,
thomas.lendacky@amd.com, x86@kernel.org
Subject: [PATCH v2] x86/kexec: avoid double free_page() upon do_kexec_load() failure.
Date: Tue, 8 May 2018 20:26:26 +0900 [thread overview]
Message-ID: <201805082026.CAD35992.LFMQtSVFFOOJOH@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20180503232922.GE30581@MiWiFi-R3L-srv>
Baoquan He wrote:
> On 05/01/18 at 07:10pm, Tetsuo Handa wrote:
> > From d54b2acf63191eba3d5052bf34fe6d26e3580ac2 Mon Sep 17 00:00:00 2001
> > From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> > Date: Tue, 1 May 2018 15:36:52 +0900
> > Subject: [PATCH] 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 explicitly setting NULL after free_page().
>
> Setting them NULL after free_page() is a good idea.
That's what the V1 patch did.
> Maybe can remove the
> double calling of free_transition_pgtable() too in init_transition_pgtable()
> because the returned value will trigger the later calling.
That's what the V2 patch did. You can apply V1 or V2 or V1 + V2.
>From 91a78abed036e1662b11cb54ae6300864e17b709 Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@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-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot <syzbot+d96f60296ef613fe1d69@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.huang@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@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
next prev parent reply other threads:[~2018-05-08 11:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-01 8:31 kernel BUG at include/linux/mm.h:LINE! syzbot
2018-05-01 10:10 ` Tetsuo Handa
2018-05-04 0:32 ` Baoquan He
2018-05-08 11:26 ` Tetsuo Handa [this message]
2018-05-09 10:42 ` [PATCH v3] x86/kexec: avoid double free_page() upon do_kexec_load() failure Tetsuo Handa
2018-05-10 6:39 ` Baoquan He
2018-05-13 17:54 ` [tip:x86/urgent] x86/kexec: Avoid " tip-bot for Tetsuo Handa
2018-05-03 21:04 ` kernel BUG at include/linux/mm.h:LINE! syzbot
2018-05-03 23:38 ` [PATCH v2] x86/kexec: avoid double free_page() upon do_kexec_load() failure Tetsuo Handa
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