This is a note to let you know that I've just added the patch titled
kexec: fix double-free when failing to relocate the purgatory
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kexec-fix-double-free-when-failing-to-relocate-the-purgatory.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 070c43eea5043e950daa423707ae3c77e2f48edb Mon Sep 17 00:00:00 2001
From: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx>
Date: Thu, 1 Sep 2016 16:14:44 -0700
Subject: kexec: fix double-free when failing to relocate the purgatory
From: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx>
commit 070c43eea5043e950daa423707ae3c77e2f48edb upstream.
If kexec_apply_relocations fails, kexec_load_purgatory frees pi->sechdrs
and pi->purgatory_buf. This is redundant, because in case of error
kimage_file_prepare_segments calls kimage_file_post_load_cleanup, which
will also free those buffers.
This causes two warnings like the following, one for pi->sechdrs and the
other for pi->purgatory_buf:
kexec-bzImage64: Loading purgatory failed
------------[ cut here ]------------
WARNING: CPU: 1 PID: 2119 at mm/vmalloc.c:1490 __vunmap+0xc1/0xd0
Trying to vfree() nonexistent vm area (ffffc90000e91000)
Modules linked in:
CPU: 1 PID: 2119 Comm: kexec Not tainted 4.8.0-rc3+ #5
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
dump_stack+0x4d/0x65
__warn+0xcb/0xf0
warn_slowpath_fmt+0x4f/0x60
? find_vmap_area+0x19/0x70
? kimage_file_post_load_cleanup+0x47/0xb0
__vunmap+0xc1/0xd0
vfree+0x2e/0x70
kimage_file_post_load_cleanup+0x5e/0xb0
SyS_kexec_file_load+0x448/0x680
? putname+0x54/0x60
? do_sys_open+0x190/0x1f0
entry_SYSCALL_64_fastpath+0x13/0x8f
---[ end trace 158bb74f5950ca2b ]---
Fix by setting pi->sechdrs an pi->purgatory_buf to NULL, since vfree
won't try to free a NULL pointer.
Link: http://lkml.kernel.org/r/1472083546-23683-1-git-send-email-bauerman@xxxxxxxxxxxxxxxxxx
Signed-off-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx>
Acked-by: Baoquan He <bhe@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/kexec_file.c | 3 +++
1 file changed, 3 insertions(+)
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -934,7 +934,10 @@ int kexec_load_purgatory(struct kimage *
return 0;
out:
vfree(pi->sechdrs);
+ pi->sechdrs = NULL;
+
vfree(pi->purgatory_buf);
+ pi->purgatory_buf = NULL;
return ret;
}
Patches currently in stable-queue which might be from bauerman@xxxxxxxxxxxxxxxxxx are
queue-4.4/kexec-fix-double-free-when-failing-to-relocate-the-purgatory.patch
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