On Tue, Jan 09, 2024 at 11:46:15AM +0800, Baoquan He wrote:
On 01/08/24 at 09:06pm, fuqiang wang wrote:
In memmap_exclude_ranges(), elfheader will be excluded from crashk_res.
In the current x86 architecture code, the elfheader is always allocated
at crashk_res.start. It seems that there won't be a new split range.
But it depends on the allocation position of elfheader in crashk_res. To
avoid potential out of bounds in future, add a extra slot.
The similar issue also exists in fill_up_crash_elf_data(). The range to
be excluded is [0, 1M], start (0) is special and will not appear in the
middle of existing cmem->ranges[]. But in cast the low 1M could be
changed in the future, add a extra slot too.
Previously discussed link:
[1] https://lore.kernel.org/kexec/ZXk2oBf%2FT1Ul6o0c@MiWiFi-R3L-srv/
[2]
https://lore.kernel.org/kexec/273284e8-7680-4f5f-8065-c5d780987...@easystack.cn/
[3] https://lore.kernel.org/kexec/ZYQ6O%2F57sHAPxTHm@MiWiFi-R3L-srv/
Signed-off-by: fuqiang wang <fuqiang.w...@easystack.cn>
---
arch/x86/kernel/crash.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index b6b044356f1b..d21592ad8952 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -149,8 +149,18 @@ static struct crash_mem *fill_up_crash_elf_data(void)
/*
* Exclusion of crash region and/or crashk_low_res may cause
* another range split. So add extra two slots here.
+ *
+ * Exclusion of low 1M may not cause another range split, because the
+ * range of exclude is [0, 1M] and the condition for splitting a new
+ * region is that the start, end parameters are both in a certain
+ * existing region in cmem and cannot be equal to existing region's
+ * start or end. Obviously, the start of [0, 1M] cannot meet this
+ * condition.
+ *
+ * But in order to lest the low 1M could be changed in the future,
+ * (e.g. [stare, 1M]), add a extra slot.
*/
- nr_ranges += 2;
+ nr_ranges += 3;
cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
if (!cmem)
return NULL;
@@ -282,9 +292,16 @@ int crash_setup_memmap_entries(struct kimage *image,
struct boot_params *params)
struct crash_memmap_data cmd;
struct crash_mem *cmem;
- cmem = vzalloc(struct_size(cmem, ranges, 1));
+ /*
+ * In the current x86 architecture code, the elfheader is always
+ * allocated at crashk_res.start. But it depends on the allocation
+ * position of elfheader in crashk_res. To avoid potential out of
+ * bounds in future, add a extra slot.
+ */
+ cmem = vzalloc(struct_size(cmem, ranges, 2));
if (!cmem)
return -ENOMEM;
+ cmem->max_nr_ranges = 2;
LGTM, thx
Acked-by: Baoquan He <b...@redhat.com>
Hi Andrew,
It seems this patch was missed. Will you pick it up? Without this patch,
kdump kernel will fail to be loaded by the kexec_file_load,
[ 139.736948] UBSAN: array-index-out-of-bounds in
arch/x86/kernel/crash.c:350:25
[ 139.742360] index 0 is out of range for type 'range [*]'
[ 139.745695] CPU: 0 UID: 0 PID: 5778 Comm: kexec Not tainted 6.15.0-0.rc3.20250425git02ddfb981de8.32.fc43.x86_64 #1 PREEMPT(lazy)
[ 139.745698] Hardware name: Amazon EC2 c5.large/, BIOS 1.0 10/16/2017
[ 139.745699] Call Trace:
[ 139.745700] <TASK>
[ 139.745701] dump_stack_lvl+0x5d/0x80
[ 139.745706] ubsan_epilogue+0x5/0x2b
[ 139.745709] __ubsan_handle_out_of_bounds.cold+0x54/0x59
[ 139.745711] crash_setup_memmap_entries+0x2d9/0x330
[ 139.745716] setup_boot_parameters+0xf8/0x6a0
[ 139.745720] bzImage64_load+0x41b/0x4e0
[ 139.745722] ? find_next_iomem_res+0x109/0x140
[ 139.745727] ? locate_mem_hole_callback+0x109/0x170
[ 139.745737] kimage_file_alloc_init+0x1ef/0x3e0
[ 139.745740] __do_sys_kexec_file_load+0x180/0x2f0
[ 139.745742] do_syscall_64+0x7b/0x160
[ 139.745745] ? do_user_addr_fault+0x21a/0x690
[ 139.745747] ? exc_page_fault+0x7e/0x1a0
[ 139.745749] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 139.745751] RIP: 0033:0x7f7712c84e4d
Thanks!
--
Best regards,
Coiby
