5.4-stable review patch. If anyone has any objections, please let me know.
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From: Arnd Bergmann arnd@arndb.de
[ 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 --- drivers/ata/sata_sx4.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/drivers/ata/sata_sx4.c b/drivers/ata/sata_sx4.c index 2c7b30c5ea3dd..eefa99ed47866 100644 --- a/drivers/ata/sata_sx4.c +++ b/drivers/ata/sata_sx4.c @@ -1004,8 +1004,7 @@ static void pdc20621_get_from_dimm(struct ata_host *host, void *psource,
offset -= (idx * window_size); idx++; - dist = ((long) (window_size - (offset + size))) >= 0 ? size : - (long) (window_size - offset); + dist = min(size, window_size - offset); memcpy_fromio(psource, dimm_mmio + offset / 4, dist);
psource += dist; @@ -1053,8 +1052,7 @@ static void pdc20621_put_to_dimm(struct ata_host *host, void *psource, readl(mmio + PDC_DIMM_WINDOW_CTLR); offset -= (idx * window_size); idx++; - dist = ((long)(s32)(window_size - (offset + size))) >= 0 ? size : - (long) (window_size - offset); + dist = min(size, window_size - offset); memcpy_toio(dimm_mmio + offset / 4, psource, dist); writel(0x01, mmio + PDC_GENERAL_CTLR); readl(mmio + PDC_GENERAL_CTLR);