4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Vasily Gorbik gor@linux.ibm.com
[ Upstream commit 6b2ddf33baec23dace85bd647e3fc4ac070963e8 ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/s390/mm/extmem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/s390/mm/extmem.c +++ b/arch/s390/mm/extmem.c @@ -79,7 +79,7 @@ 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; @@ -432,7 +432,7 @@ __segment_load (char *name, int do_nonsh 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 ||