Patch "regmap: maple: Fix cache corruption in regcache_maple_drop()" has been added to the 6.8-stable tree

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

    regmap: maple: Fix cache corruption in regcache_maple_drop()

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:
     regmap-maple-fix-cache-corruption-in-regcache_maple_.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 5d8ac6fd9d36152f5ff13a69877099ab3e7546b2
Author: Richard Fitzgerald <rf@xxxxxxxxxxxxxxxxxxxxx>
Date:   Wed Mar 27 11:44:06 2024 +0000

    regmap: maple: Fix cache corruption in regcache_maple_drop()
    
    [ Upstream commit 00bb549d7d63a21532e76e4a334d7807a54d9f31 ]
    
    When keeping the upper end of a cache block entry, the entry[] array
    must be indexed by the offset from the base register of the block,
    i.e. max - mas.index.
    
    The code was indexing entry[] by only the register address, leading
    to an out-of-bounds access that copied some part of the kernel
    memory over the cache contents.
    
    This bug was not detected by the regmap KUnit test because it only
    tests with a block of registers starting at 0, so mas.index == 0.
    
    Signed-off-by: Richard Fitzgerald <rf@xxxxxxxxxxxxxxxxxxxxx>
    Fixes: f033c26de5a5 ("regmap: Add maple tree based register cache")
    Link: https://msgid.link/r/20240327114406.976986-1-rf@xxxxxxxxxxxxxxxxxxxxx
    Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/base/regmap/regcache-maple.c b/drivers/base/regmap/regcache-maple.c
index 41edd6a430eb4..c1776127a5724 100644
--- a/drivers/base/regmap/regcache-maple.c
+++ b/drivers/base/regmap/regcache-maple.c
@@ -145,7 +145,7 @@ static int regcache_maple_drop(struct regmap *map, unsigned int min,
 			upper_index = max + 1;
 			upper_last = mas.last;
 
-			upper = kmemdup(&entry[max + 1],
+			upper = kmemdup(&entry[max - mas.index + 1],
 					((mas.last - max) *
 					 sizeof(unsigned long)),
 					map->alloc_flags);




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