[PATCH 1/2] sadump: set info->page_size before cache_init()

[Atsushi Kumagai]

>On Tuesday 23 May 2017 08:22 AM, Hatayama, Daisuke wrote:
>> Currently, makedumpfile results in Segmentation fault on sadump dump
>> files as follows:
>>
>>     # LANG=C makedumpfile -f --message-level=31 -ld31 -x vmlinux ./sadump_vmcore sadump_vmcore-ld31
>>     sadump: read dump device as single partition
>>     sadump: single partition configuration
>>     page_size    : 4096
>>     sadump: timezone information is missing
>>     Segmentation fault
>>
>> By bisect, I found that this issue is caused by the following commit
>> that moves invocation of cache_init() in initial() a bit early:
>>
>>     # git bisect bad
>>     8e2834bac4f62da3894da297f083068431be6d80 is the first bad commit
>>     commit 8e2834bac4f62da3894da297f083068431be6d80
>>     Author: Pratyush Anand <panand at redhat.com>
>>     Date:   Thu Mar 2 17:37:11 2017 +0900
>>
>>         [PATCH v3 2/7] initial(): call cache_init() a bit early
>>
>>         Call cache_init() before get_kcore_dump_loads(), because latter uses
>>         cache_search().
>>
>>         Call path is like this :
>>         get_kcore_dump_loads() -> process_dump_load() -> vaddr_to_paddr() ->
>>         vtop4_x86_64() -> readmem() -> cache_search()
>>
>>         Signed-off-by: Pratyush Anand <panand at redhat.com>
>>
>>     :100644 100644 6942047199deb09dd1fff2121e264584dbb05587 3b8e9810468de26b0d8b73d456f0bd4f3d3aa2fe M
>makedumpfile.c
>>
>> In this timing, on sadump vmcores, info->page_size has not been
>> initialized yet so has 0. So, malloc() in cache_init() returns a chunk
>> of 0 size. A bit later, info->page_size is initialized with 4096.
>> Later processing on cache.c behaves assuming the chunk size is 8 *
>> 4096. This destroys objects allocated after the chunk, resulting in
>> the above Segmentation fault.
>>
>> To fix this issue, this commit moves setting info->page_size before
>> cache_init().
>>
>> Signed-off-by: HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com>
>> Cc: Pratyush Anand <panand at redhat.com>
>
>For 1/2
>Reviewed-by: Pratyush Anand <panand at redhat.com>

Thanks for your work, I'll merge this patch into v1.6.2.

Regards,
Atsushi Kumagai

>> ---
>>  makedumpfile.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/makedumpfile.c b/makedumpfile.c
>> index 301772a..f300b19 100644
>> --- a/makedumpfile.c
>> +++ b/makedumpfile.c
>> @@ -3878,6 +3878,9 @@ initial(void)
>>  	if (!get_value_for_old_linux())
>>  		return FALSE;
>>
>> +	if (info->flag_sadump && !set_page_size(sadump_page_size()))
>> +			return FALSE;
>> +
>>  	if (!is_xen_memory() && !cache_init())
>>  		return FALSE;
>>
>> @@ -3906,9 +3909,6 @@ initial(void)
>>  			return FALSE;
>>  		}
>>
>> -		if (!set_page_size(sadump_page_size()))
>> -			return FALSE;
>> -
>>  		if (!sadump_initialize_bitmap_memory())
>>  			return FALSE;
>>
>>
>
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