This is a note to let you know that I've just added the patch titled
lz4: add overrun checks to lz4_uncompress_unknownoutputsize()
to my driver-core git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git
in the driver-core-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 4a3a99045177369700c60d074c0e525e8093b0fc Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Date: Thu, 3 Jul 2014 16:06:57 -0700
Subject: lz4: add overrun checks to lz4_uncompress_unknownoutputsize()
Jan points out that I forgot to make the needed fixes to the
lz4_uncompress_unknownoutputsize() function to mirror the changes done
in lz4_decompress() with regards to potential pointer overflows.
The only in-kernel user of this function is the zram code, which only
takes data from a valid compressed buffer that it made itself, so it's
not a big issue. But due to external kernel modules using this
function, it's better to be safe here.
Reported-by: Jan Beulich <JBeulich@xxxxxxxx>
Cc: "Don A. Bailey" <donb@xxxxxxxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
lib/lz4/lz4_decompress.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c
index b74da447e81e..7a85967060a5 100644
--- a/lib/lz4/lz4_decompress.c
+++ b/lib/lz4/lz4_decompress.c
@@ -192,6 +192,8 @@ static int lz4_uncompress_unknownoutputsize(const char *source, char *dest,
int s = 255;
while ((ip < iend) && (s == 255)) {
s = *ip++;
+ if (unlikely(length > (size_t)(length + s)))
+ goto _output_error;
length += s;
}
}
@@ -232,6 +234,8 @@ static int lz4_uncompress_unknownoutputsize(const char *source, char *dest,
if (length == ML_MASK) {
while (ip < iend) {
int s = *ip++;
+ if (unlikely(length > (size_t)(length + s)))
+ goto _output_error;
length += s;
if (s == 255)
continue;
@@ -284,7 +288,7 @@ static int lz4_uncompress_unknownoutputsize(const char *source, char *dest,
/* write overflow error detected */
_output_error:
- return (int) (-(((char *) ip) - source));
+ return -1;
}
int lz4_decompress(const unsigned char *src, size_t *src_len,
--
2.0.0.254.g50f84e3
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