From: Jerome Marchand jmarchan@redhat.com
[ Upstream commit a0651926553cfe7992166432e418987760882652 ]
For the first call to realloc_argv() in dm_split_args(), old_argv is NULL and size is zero. Then memcpy is called, with the NULL old_argv as the source argument and a zero size argument. AFAIK, this is undefined behavior and generates the following warning when compiled with UBSAN on ppc64le:
In file included from ./arch/powerpc/include/asm/paca.h:19, from ./arch/powerpc/include/asm/current.h:16, from ./include/linux/sched.h:12, from ./include/linux/kthread.h:6, from drivers/md/dm-core.h:12, from drivers/md/dm-table.c:8: In function 'memcpy', inlined from 'realloc_argv' at drivers/md/dm-table.c:565:3, inlined from 'dm_split_args' at drivers/md/dm-table.c:588:9: ./include/linux/string.h:345:9: error: argument 2 null where non-null expected [-Werror=nonnull] return __builtin_memcpy(p, q, size); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/md/dm-table.c: In function 'dm_split_args': ./include/linux/string.h:345:9: note: in a call to built-in function '__builtin_memcpy'
Signed-off-by: Jerome Marchand jmarchan@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/dm-table.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 350cf0451456..ec8b27e20de3 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -561,7 +561,7 @@ static char **realloc_argv(unsigned *size, char **old_argv) gfp = GFP_NOIO; } argv = kmalloc_array(new_size, sizeof(*argv), gfp); - if (argv) { + if (argv && old_argv) { memcpy(argv, old_argv, *size * sizeof(*argv)); *size = new_size; }