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; } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
