The patch titled
Subject: kexec: fix double-free when failing to relocate the purgatory
has been added to the -mm tree. Its filename is
kexec-fix-double-free-when-failing-to-relocate-the-purgatory.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kexec-fix-double-free-when-failing-to-relocate-the-purgatory.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kexec-fix-double-free-when-failing-to-relocate-the-purgatory.patch
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------------------------------------------------------
From: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx>
Subject: kexec: fix double-free when failing to relocate the purgatory
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.
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>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/kexec_file.c | 3 +++
1 file changed, 3 insertions(+)
diff -puN kernel/kexec_file.c~kexec-fix-double-free-when-failing-to-relocate-the-purgatory kernel/kexec_file.c
--- a/kernel/kexec_file.c~kexec-fix-double-free-when-failing-to-relocate-the-purgatory
+++ a/kernel/kexec_file.c
@@ -887,7 +887,10 @@ 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 -mm which might be from bauerman@xxxxxxxxxxxxxxxxxx are
kexec-fix-double-free-when-failing-to-relocate-the-purgatory.patch
kexec_file-allow-arch-specific-memory-walking-for-kexec_add_buffer.patch
kexec_file-change-kexec_add_buffer-to-take-kexec_buf-as-argument.patch
kexec_file-factor-out-kexec_locate_mem_hole-from-kexec_add_buffer.patch
powerpc-factor-out-relocation-code-from-module_64c-to-elf_util_64c.patch
powerpc-generalize-elf64_apply_relocate_add.patch
powerpc-adapt-elf64_apply_relocate_add-for-kexec_file_load.patch
powerpc-add-functions-to-read-elf-files-of-any-endianness.patch
powerpc-implement-kexec_file_load.patch
powerpc-add-code-to-work-with-device-trees-in-kexec_file_load.patch
powerpc-add-support-for-loading-elf-kernels-with-kexec_file_load.patch
powerpc-add-purgatory-for-kexec_file_load-implementation.patch
powerpc-enable-config_kexec_file-in-powerpc-server-defconfigs.patch
kexec_file-add-buffer-hand-over-support-for-the-next-kernel.patch
powerpc-kexec_file-add-buffer-hand-over-support-for-the-next-kernel.patch
kexec_file-allow-skipping-checksum-calculation-for-some-segments.patch
kexec_file-add-mechanism-to-update-kexec-segments.patch
ima-demonstration-code-for-kexec-buffer-passing.patch
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