The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: 5849cdf8c120e3979c57d34be55b92d90a77a47e
Gitweb: https://git.kernel.org/tip/5849cdf8c120e3979c57d34be55b92d90a77a47e
Author: Mike Galbraith <efault@xxxxxx>
AuthorDate: Fri, 16 Apr 2021 14:02:07 +02:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Tue, 20 Apr 2021 17:32:46 +02:00
x86/crash: Fix crash_setup_memmap_entries() out-of-bounds access
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 <efault@xxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Dave Young <dyoung@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/725fa3dc1da2737f0f6188a1a9701bead257ea9d.camel@xxxxxx
---
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 a8f3af2..b1deacb 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;
|