From: Mike Galbraith efault@gmx.de
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 efault@gmx.de Signed-off-by: Borislav Petkov bp@suse.de Reviewed-by: Dave Young dyoung@redhat.com Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/725fa3dc1da2737f0f6188a1a9701bead257ea9d.camel@gmx... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/crash.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -23,6 +23,7 @@ #include <linux/export.h> #include <linux/slab.h> #include <linux/vmalloc.h> +#include <linux/overflow.h>
#include <asm/processor.h> #include <asm/hardirq.h> @@ -565,7 +566,7 @@ int crash_setup_memmap_entries(struct ki 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;