From: Linus Torvalds torvalds@linux-foundation.org
[ Upstream commit fc7c028dcdbfe981bca75d2a7b95f363eb691ef3 ]
The sparc mdesc code does pointer games with 'struct mdesc_hdr', but didn't describe to the compiler how that header is then followed by the data that the header describes.
As a result, gcc is now unhappy since it does stricter pointer range tracking, and doesn't understand about how these things work. This results in various errors like:
arch/sparc/kernel/mdesc.c: In function ‘mdesc_node_by_name’: arch/sparc/kernel/mdesc.c:647:22: error: ‘strcmp’ reading 1 or more bytes from a region of size 0 [-Werror=stringop-overread] 647 | if (!strcmp(names + ep[ret].name_offset, name)) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
which are easily avoided by just describing 'struct mdesc_hdr' better, and making the node_block() helper function look into that unsized data[] that follows the header.
This makes the sparc64 build happy again at least for my cross-compiler version (gcc version 11.2.1).
Link: https://lore.kernel.org/lkml/CAHk-=wi4NW3NC0xWykkw=6LnjQD6D_rtRtxY9g8gQAJXtQ... Cc: Guenter Roeck linux@roeck-us.net Cc: David S. Miller davem@davemloft.net Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/sparc/kernel/mdesc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/sparc/kernel/mdesc.c b/arch/sparc/kernel/mdesc.c index 6f80936e0eea..75445ba7e237 100644 --- a/arch/sparc/kernel/mdesc.c +++ b/arch/sparc/kernel/mdesc.c @@ -37,6 +37,7 @@ struct mdesc_hdr { u32 node_sz; /* node block size */ u32 name_sz; /* name block size */ u32 data_sz; /* data block size */ + char data[]; } __attribute__((aligned(16)));
struct mdesc_elem { @@ -369,7 +370,7 @@ void mdesc_update(void)
static struct mdesc_elem *node_block(struct mdesc_hdr *mdesc) { - return (struct mdesc_elem *) (mdesc + 1); + return (struct mdesc_elem *) mdesc->data; }
static void *name_block(struct mdesc_hdr *mdesc)