Because of structure member alignment, the simple structure
struct kdump_sub_header {
unsigned long phys_base;
int dump_level;
};
is 16 bytes large on x86_64. So if you fill the two members phys_base and
dump_level with values, you still have uninitialised memory if you write
sizeof(struct kdump_sub_header) to disk.
This patch initialises everything with zero first to get rid of that problem.
The patch fixes valgrind warning
==24152== Syscall param write(buf) points to uninitialised byte(s)
==24152== at 0x4EEFFC0: write (in /lib64/libc-2.8.so)
==24152== by 0x40A97D: (within /bin/makedumpfile)
==24152== by 0x40ACEF: (within /bin/makedumpfile)
==24152== by 0x41896C: (within /bin/makedumpfile)
==24152== by 0x4191AA: (within /bin/makedumpfile)
==24152== by 0x4E48435: (below main) (in /lib64/libc-2.8.so)
==24152== Address 0x7fefffbfc is on thread 1's stack
Signed-off-by: Bernhard Walle <bwalle at suse.de>
---
makedumpfile.c | 1 +
1 file changed, 1 insertion(+)
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -4707,6 +4707,7 @@ write_kdump_header(void)
/*
* Write sub header
*/
+ memset(&sub_dump_header, 0, sizeof(struct kdump_sub_header));
sub_dump_header.phys_base = info->phys_base;
sub_dump_header.dump_level = info->dump_level;
size = sizeof(struct kdump_sub_header);
