On 05/08/25 at 03:38pm, Baoquan He 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. And using > random kexec_buf for passing dm crypt keys may cause a range split too, > add another extra slot here.
Sorry, this should be from fuqiang wang, when I edited the patch to reply to his patch, I forgot that. Please help makes change to set Fuqiang as the patch author, I just adapted the content based on Coiby's patches. > > 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> > Signed-off-by: Baoquan He <b...@redhat.com> > --- > v4->v5: > - This is on top of Coiby's LUKS patchset in branch mm-nonmm-unstable of > akpm/mm.git. I did some adaption based on Coiby's patches. > - [PATCH v9 0/8] Support kdump with LUKS encryption by reusing LUKS volume > keys > > arch/x86/kernel/crash.c | 23 +++++++++++++++++++---- > 1 file changed, 19 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c > index bcb534688dfe..749a60ce8b7f 100644 > --- a/arch/x86/kernel/crash.c > +++ b/arch/x86/kernel/crash.c > @@ -165,8 +165,18 @@ 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; > @@ -313,10 +323,15 @@ int crash_setup_memmap_entries(struct kimage *image, > struct boot_params *params) > struct crash_mem *cmem; > > /* > - * Using random kexec_buf for passing dm crypt keys may cause a range > - * split. So use two slots here. > + * 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 an extra slot. > + * > + * And using random kexec_buf for passing dm crypt keys may cause a > + * range split too, add another extra slot here. > */ > - nr_ranges = 2; > + nr_ranges = 3; > cmem = vzalloc(struct_size(cmem, ranges, nr_ranges)); > if (!cmem) > return -ENOMEM; > -- > 2.41.0 >
