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/[email protected]/
[3] https://lore.kernel.org/kexec/ZYQ6O%2F57sHAPxTHm@MiWiFi-R3L-srv/
Signed-off-by: fuqiang wang <[email protected]>
---
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;
memset(&cmd, 0, sizeof(struct crash_memmap_data));
cmd.params = params;
--
2.42.0
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/[email protected]/
> [3] https://lore.kernel.org/kexec/ZYQ6O%2F57sHAPxTHm@MiWiFi-R3L-srv/
>
> Signed-off-by: fuqiang wang <[email protected]>
> ---
> 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 <[email protected]>
>
> memset(&cmd, 0, sizeof(struct crash_memmap_data));
> cmd.params = params;
> --
> 2.42.0
>