On Wednesday 24 May 2017 11:41 AM, Atsushi Kumagai wrote:
On Tuesday 23 May 2017 08:39 AM, Atsushi Kumagai wrote:
Thanks for your report, I have received this.
I'm on vacation until Mar 8, I'll review it when I return from vacation.
Any further comment on it?
Otherwise, I will send a v2 after accommodating concern from Xunlei.
Unfortunately, it doesn't seem like I can make time anymore for review this
week,
but at least this patch doesn't seem to work in my environment (linux 4.8
without kaslr).
Do you have any ideas ?
I see, why it would have caused. I have not tested this case, but I hope my v2
should not have this issue.
Umm, v2 still doesn't work in my environment...
It seems that I have to investigate this deeper.
Hummm, I thought we would see file_vmcoreinfo as NULL in
get_kaslr_offset_x86_64() in your case. However, it's not true.
I think, it will have to be initialized with NULL in main().
Can you please try following fixup on top of this series:
I found the cause, please see below:
initial()
+ find_kaslr_offsets()
+ open_vmcoreinfo()
+ get_kaslr_offset() // set info->kaslr_offset
+ close_vmcoreinfo()
gather_filter_info()
(snip)
+ resolve_config_entry()
+ get_kaslr_offset() // occur SIGSEGV since info->file_vmcoreinfo is
closed
Since info->file_vmcoreinfo is closed,therefore it should be NULL. But
currently, close_vmcoreinfo() does not set it to NULL. We should also set
info->file_vmcoreinfo to NULL in close_vmcoreinfo() apart from main().
Sure, uninitialized info->file_vmcoreinfo is a general issue,
I'll fix it in another patch.
I will be sending v2 today which should also fix issue seen by Hatayama,
Daisuke.
http://lists.infradead.org/pipermail/kexec/2017-May/018833.html
~Pratyush
The cause code is in [PATCH v2 1/2],
diff --git a/erase_info.c b/erase_info.c
index f2ba914..60abfa1 100644
--- a/erase_info.c
+++ b/erase_info.c
@@ -1088,6 +1088,7 @@ resolve_config_entry(struct config_entry *ce, unsigned
long long base_vaddr,
ce->line, ce->name);
return FALSE;
}
+ ce->sym_addr += get_kaslr_offset(ce->sym_addr);
ce->type_name = get_symbol_type_name(ce->name,
DWARF_INFO_GET_SYMBOL_TYPE,
&ce->size, &ce->type_flag);
I think we should use info->kaslr_offset instead of get_kaslr_offset(),
how about you ?
Actually, we are not sure at this point that ce->sym_addr is a kernel linear
address. It could be a module address and that can have different
randomization offset.
I see, I misunderstood that the randomization offset is same in any case.
My intention is to calculate all types of kaslr offsets in
find_kaslr_offsets() very early and then store them in different "info"
elements. Now, whenever we call get_kaslr_offset() we would return right
offset as per the input address.
I have very little idea about x86. So, I have left a TODO to calculate offset
for non-linear addresses.
BTW, I'm not sure why you didn't meet this issue...
Because, I tested with kaslr kernel, so when get_kaslr_offset(ce->sym_addr)
was called, I already had a valid info->kaslr_offset.
So, what about following fixup
As mentioned at the beginning, the fix below is not your fault,
so I'll merge your patches as it is into v1.6.2.
diff --git a/makedumpfile.c b/makedumpfile.c
index 57235690569e..4986d098d69a 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -8685,6 +8685,7 @@ close_vmcoreinfo(void)
if(fclose(info->file_vmcoreinfo) < 0)
ERRMSG("Can't close the vmcoreinfo file(%s). %s\n",
info->name_vmcoreinfo, strerror(errno));
+ info->file_vmcoreinfo = NULL;
}
void
@@ -11076,6 +11077,7 @@ main(int argc, char *argv[])
strerror(errno));
goto out;
}
+ info->file_vmcoreinfo = NULL;
info->fd_vmlinux = -1;
info->fd_xen_syms = -1;
info->fd_memory = -1;
However, I think [PATCH 2/2] should be dropped since the alternative patch
has appeared, is it ok with you ?
https://github.com/pratyushanand/makedumpfile/commit/16655ce1f4c2da8d4066072db2a03c84bf2553fe
Thanks,
Atsushi Kumagai
~Pratyush
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