[ Upstream commit 52f80bb181a9a1530ade30bc18991900bbb9697f ]
gcc warns about a memcpy() with overlapping pointers because of an
incorrect size calculation:
In file included from include/linux/string.h:369,
from drivers/ata/sata_sx4.c:66:
In function 'memcpy_fromio',
inlined from 'pdc20621_get_from_dimm.constprop' at drivers/ata/sata_sx4.c:962:2:
include/linux/fortify-string.h:97:33: error: '__builtin_memcpy' accessing 4294934464 bytes at offsets 0 and [16, 16400] overlaps 6442385281 bytes at offset -2147450817 [-Werror=restrict]
97 | #define __underlying_memcpy __builtin_memcpy
| ^
include/linux/fortify-string.h:620:9: note: in expansion of macro '__underlying_memcpy'
620 | __underlying_##op(p, q, __fortify_size); \
| ^~~~~~~~~~~~~
include/linux/fortify-string.h:665:26: note: in expansion of macro '__fortify_memcpy_chk'
665 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \
| ^~~~~~~~~~~~~~~~~~~~
include/asm-generic/io.h:1184:9: note: in expansion of macro 'memcpy'
1184 | memcpy(buffer, __io_virt(addr), size);
| ^~~~~~
The problem here is the overflow of an unsigned 32-bit number to a
negative that gets converted into a signed 'long', keeping a large
positive number.
Replace the complex calculation with a more readable min() variant
that avoids the warning.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
