This is a note to let you know that I've just added the patch titled
sparc: avoid stringop-overread errors
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sparc-avoid-stringop-overread-errors.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 6ce53f7562a377e4cb151add6b6133ecdeb985c1
Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date: Mon Sep 6 16:06:04 2021 -0700
sparc: avoid stringop-overread errors
[ 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_rtRtxY9g8gQAJXtQMi8A@xxxxxxxxxxxxxx/
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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)
