Patch "ata: sata_sx4: fix pdc20621_get_from_dimm() on 64-bit" has been added to the 6.8-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    ata: sata_sx4: fix pdc20621_get_from_dimm() on 64-bit

to the 6.8-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:
     ata-sata_sx4-fix-pdc20621_get_from_dimm-on-64-bit.patch
and it can be found in the queue-6.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit e247c8ed8ba9824536d0f71a27f75700c81e13df
Author: Arnd Bergmann <arnd@xxxxxxxx>
Date:   Tue Mar 26 15:53:37 2024 +0100

    ata: sata_sx4: fix pdc20621_get_from_dimm() on 64-bit
    
    [ 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@xxxxxxxx>
    Signed-off-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/ata/sata_sx4.c b/drivers/ata/sata_sx4.c
index b51d7a9d0d90c..a482741eb181f 100644
--- a/drivers/ata/sata_sx4.c
+++ b/drivers/ata/sata_sx4.c
@@ -957,8 +957,7 @@ 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;
@@ -1005,8 +1004,7 @@ 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);