From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Guenter Roeck <linux@roeck-us.net>,
"David S . Miller" <davem@davemloft.net>,
Sasha Levin <sashal@kernel.org>,
sparclinux@vger.kernel.org
Subject: [PATCH AUTOSEL 4.9 05/11] sparc: avoid stringop-overread errors
Date: Wed, 22 Sep 2021 23:40:21 -0400 [thread overview]
Message-ID: <20210923034028.1421876-5-sashal@kernel.org> (raw)
In-Reply-To: <20210923034028.1421876-1-sashal@kernel.org>
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_rtRtxY9g8gQAJXtQMi8A@mail.gmail.com/
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 8a6982dfd733..5aa33bf7139e 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)
--
2.30.2
next prev parent reply other threads:[~2021-09-23 3:43 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 3:40 [PATCH AUTOSEL 4.9 01/11] net: stmmac: allow CSR clock of 300MHz Sasha Levin
2021-09-23 3:40 ` [PATCH AUTOSEL 4.9 02/11] m68k: Double cast io functions to unsigned long Sasha Levin
2021-09-23 3:40 ` [PATCH AUTOSEL 4.9 03/11] compiler.h: Introduce absolute_pointer macro Sasha Levin
2021-09-23 3:40 ` [PATCH AUTOSEL 4.9 04/11] net: i825xx: Use absolute_pointer for memcpy from fixed memory location Sasha Levin
2021-09-23 3:40 ` Sasha Levin [this message]
2021-09-23 3:40 ` [PATCH AUTOSEL 4.9 06/11] qnx4: avoid stringop-overread errors Sasha Levin
2021-09-23 3:40 ` [PATCH AUTOSEL 4.9 07/11] parisc: Use absolute_pointer() to define PAGE0 Sasha Levin
2021-09-23 3:40 ` [PATCH AUTOSEL 4.9 08/11] arm64: Mark __stack_chk_guard as __ro_after_init Sasha Levin
2021-09-23 3:40 ` [PATCH AUTOSEL 4.9 09/11] alpha: Declare virt_to_phys and virt_to_bus parameter as pointer to volatile Sasha Levin
2021-09-23 3:40 ` [PATCH AUTOSEL 4.9 10/11] net: 6pack: Fix tx timeout and slot time Sasha Levin
2021-09-23 3:40 ` [PATCH AUTOSEL 4.9 11/11] spi: Fix tegra20 build with CONFIG_PM=n Sasha Levin
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