Commit 6b2ddf33 authored Jun 17, 2018 by Vasily Gorbik Committed by Martin Schwidefsky Jul 02, 2018

s390/extmem: fix gcc 8 stringop-overflow warning



arch/s390/mm/extmem.c: In function '__segment_load':
arch/s390/mm/extmem.c:436:2: warning: 'strncat' specified bound 7 equals
source length [-Wstringop-overflow=]
  strncat(seg->res_name, " (DCSS)", 7);

What gcc complains about here is the misuse of strncat function, which
in this case does not limit a number of bytes taken from "src", so it is
in the end the same as strcat(seg->res_name, " (DCSS)");

Keeping in mind that a res_name is 15 bytes, strncat in this case
would overflow the buffer and write 0 into alignment byte between the
fields in the struct. To avoid that increasing res_name size to 16,
and reusing strlcat.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

parent d642d626

arch/s390/mm/extmem.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -80,7 +80,7 @@ struct qin64 {
		struct dcss_segment {
		struct list_head list;
		char dcss_name[8];
		char res_name[15];
		char res_name[16];
		unsigned long start_addr;
		unsigned long end;
		atomic_t ref_count;
		@@ -433,7 +433,7 @@ __segment_load (char name, int do_nonshared, unsigned long addr, unsigned long
		memcpy(&seg->res_name, seg->dcss_name, 8);
		EBCASC(seg->res_name, 8);
		seg->res_name[8] = '\0';
		strncat(seg->res_name, " (DCSS)", 7);
		strlcat(seg->res_name, " (DCSS)", sizeof(seg->res_name));
		seg->res->name = seg->res_name;
		rc = seg->vm_segtype;
		if (rc == SEG_TYPE_SC \|\|

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