From 042bc760eed861f7f4f06bcb26054ef7ca3741e8 Mon Sep 17 00:00:00 2001 From: Mike Galbraith Date: Fri, 7 May 2021 07:57:21 +0000 Subject: [PATCH] x86/crash: Fix crash_setup_memmap_entries() out-of-bounds access stable inclusion from stable-5.10.33 commit 31720f9e87c032b74de9661e67cfc01414d27052 bugzilla: 51834 CVE: NA -------------------------------- commit 5849cdf8c120e3979c57d34be55b92d90a77a47e upstream. Commit in Fixes: added support for kexec-ing a kernel on panic using a new system call. As part of it, it does prepare a memory map for the new kernel. However, while doing so, it wrongly accesses memory it has not allocated: it accesses the first element of the cmem->ranges[] array in memmap_exclude_ranges() but it has not allocated the memory for it in crash_setup_memmap_entries(). As KASAN reports: BUG: KASAN: vmalloc-out-of-bounds in crash_setup_memmap_entries+0x17e/0x3a0 Write of size 8 at addr ffffc90000426008 by task kexec/1187 (gdb) list *crash_setup_memmap_entries+0x17e 0xffffffff8107cafe is in crash_setup_memmap_entries (arch/x86/kernel/crash.c:322). 317 unsigned long long mend) 318 { 319 unsigned long start, end; 320 321 cmem->ranges[0].start = mstart; 322 cmem->ranges[0].end = mend; 323 cmem->nr_ranges = 1; 324 325 /* Exclude elf header region */ 326 start = image->arch.elf_load_addr; (gdb) Make sure the ranges array becomes a single element allocated. [ bp: Write a proper commit message. ] Fixes: dd5f726076cc ("kexec: support for kexec on panic using new system call") Signed-off-by: Mike Galbraith Signed-off-by: Borislav Petkov Reviewed-by: Dave Young Cc: Link: https://lkml.kernel.org/r/725fa3dc1da2737f0f6188a1a9701bead257ea9d.camel@gmx.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Chen Jun Acked-by: Weilong Chen Signed-off-by: Zheng Zengkai --- arch/x86/kernel/crash.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index 9d0722fb8842..54ce999ed321 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -337,7 +337,7 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params) struct crash_memmap_data cmd; struct crash_mem *cmem; - cmem = vzalloc(sizeof(struct crash_mem)); + cmem = vzalloc(struct_size(cmem, ranges, 1)); if (!cmem) return -ENOMEM; -- GitLab