From: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
To: kexec@lists.infradead.org
Cc: Eric Biederman <ebiederm@xmission.com>,
Dave Young <dyoung@redhat.com>, Vivek Goyal <vgoyal@redhat.com>,
Baoquan He <bhe@redhat.com>,
linux-kernel@vger.kernel.org,
Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Subject: [PATCH] kexec: Fix double-free when failing to relocate the purgatory.
Date: Wed, 24 Aug 2016 21:05:46 -0300 [thread overview]
Message-ID: <1472083546-23683-1-git-send-email-bauerman@linux.vnet.ibm.com> (raw)
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:
[ 18.112843] kexec-bzImage64: Loading purgatory failed
[ 18.113257] ------------[ cut here ]------------
[ 18.113263] WARNING: CPU: 1 PID: 2119 at mm/vmalloc.c:1490 __vunmap+0xc1/0xd0
[ 18.113264] Trying to vfree() nonexistent vm area (ffffc90000e91000)
[ 18.113367] Modules linked in:
[ 18.113371] CPU: 1 PID: 2119 Comm: kexec Not tainted 4.8.0-rc3+ #5
[ 18.113372] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
[ 18.113373] 0000000000000000 ffff88003bbb7dc8 ffffffff8132eca8 ffff88003bbb7e18
[ 18.113376] 0000000000000000 ffff88003bbb7e08 ffffffff8105f1bb 000005d281175bf8
[ 18.113377] ffffc90000e91000 0000000000000000 0000000000000001 ffff88003e5f8c00
[ 18.113379] Call Trace:
[ 18.113384] [<ffffffff8132eca8>] dump_stack+0x4d/0x65
[ 18.113386] [<ffffffff8105f1bb>] __warn+0xcb/0xf0
[ 18.113388] [<ffffffff8105f22f>] warn_slowpath_fmt+0x4f/0x60
[ 18.113390] [<ffffffff81176469>] ? find_vmap_area+0x19/0x70
[ 18.113393] [<ffffffff810dbb57>] ? kimage_file_post_load_cleanup+0x47/0xb0
[ 18.113394] [<ffffffff81177451>] __vunmap+0xc1/0xd0
[ 18.113396] [<ffffffff811774ce>] vfree+0x2e/0x70
[ 18.113397] [<ffffffff810dbb6e>] kimage_file_post_load_cleanup+0x5e/0xb0
[ 18.113398] [<ffffffff810dc718>] SyS_kexec_file_load+0x448/0x680
[ 18.113401] [<ffffffff811a6834>] ? putname+0x54/0x60
[ 18.113403] [<ffffffff81195d70>] ? do_sys_open+0x190/0x1f0
[ 18.113407] [<ffffffff81824e5b>] entry_SYSCALL_64_fastpath+0x13/0x8f
[ 18.113408] ---[ end trace 158bb74f5950ca2b ]---
Fix by setting pi->sechdrs an pi->purgatory_buf to NULL, since vfree
won't try to free a NULL pointer.
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
---
kernel/kexec_file.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 503bc2d348e5..037c321c5618 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -887,7 +887,10 @@ int kexec_load_purgatory(struct kimage *image, unsigned long min,
return 0;
out:
vfree(pi->sechdrs);
+ pi->sechdrs = NULL;
+
vfree(pi->purgatory_buf);
+ pi->purgatory_buf = NULL;
return ret;
}
--
1.9.1
next reply other threads:[~2016-08-25 7:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-25 0:05 Thiago Jung Bauermann [this message]
2016-08-25 1:40 ` [PATCH] kexec: Fix double-free when failing to relocate the purgatory Baoquan He
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1472083546-23683-1-git-send-email-bauerman@linux.vnet.ibm.com \
--to=bauerman@linux.vnet.ibm.com \
--cc=bhe@redhat.com \
--cc=dyoung@redhat.com \
--cc=ebiederm@xmission.com \
--cc=kexec@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=vgoyal@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).