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[01/11] x86: compressed: avoid gcc-11 -Wstringop-overread warning

Message ID 20210322160253.4032422-2-arnd@kernel.org
State New
Headers show
Series [01/11] x86: compressed: avoid gcc-11 -Wstringop-overread warning | expand

Commit Message

Arnd Bergmann March 22, 2021, 4:02 p.m. UTC
From: Arnd Bergmann <arnd@arndb.de>

gcc gets confused by the comparison of a pointer to an integer listeral,
with the assumption that this is an offset from a NULL pointer and that
dereferencing it is invalid:

In file included from arch/x86/boot/compressed/misc.c:18:
In function ‘parse_elf’,
    inlined from ‘extract_kernel’ at arch/x86/boot/compressed/misc.c:442:2:
arch/x86/boot/compressed/../string.h:15:23: error: ‘__builtin_memcpy’ reading 64 bytes from a region of size 0 [-Werror=stringop-overread]
   15 | #define memcpy(d,s,l) __builtin_memcpy(d,s,l)
      |                       ^~~~~~~~~~~~~~~~~~~~~~~
arch/x86/boot/compressed/misc.c:283:9: note: in expansion of macro ‘memcpy’
  283 |         memcpy(&ehdr, output, sizeof(ehdr));
      |         ^~~~~~

I could not find any good workaround for this, but as this is only
a warning for a failure during early boot, removing the line entirely
works around the warning.

This should probably get addressed in gcc instead, before 11.1 gets

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
 arch/x86/boot/compressed/misc.c | 2 --
 1 file changed, 2 deletions(-)
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diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 3a214cc3239f..9ada64e66cb7 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -430,8 +430,6 @@  asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
 		error("Destination address too large");
-	if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
-		error("Destination address does not match LOAD_PHYSICAL_ADDR");
 	if (virt_addr != LOAD_PHYSICAL_ADDR)
 		error("Destination virtual address changed when not relocatable");