From: Linus Torvalds <torvalds@linux-foundation.org> stable inclusion from stable-5.10.70 commit 5520d27f02a15831e240e14c1f1a19ea6b3f467f bugzilla: 182949 https://gitee.com/openeuler/kernel/issues/I4I3GQ Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ 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> Signed-off-by: Chen Jun <chenjun102@huawei.com> Acked-by: Weilong Chen <chenweilong@huawei.com> Signed-off-by: Chen Jun <chenjun102@huawei.com> --- 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 8e645ddac58e..30f171b7b00c 100644 --- a/arch/sparc/kernel/mdesc.c +++ b/arch/sparc/kernel/mdesc.c @@ -39,6 +39,7 @@ 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 { @@ -612,7 +613,7 @@ EXPORT_SYMBOL(mdesc_get_node_info); 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) -- 2.20.1