linux-kernel - Re: lz4: fix system halted at boot kernel x86

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Date:	Fri, 3 Apr 2015 16:30:40 +0200
From:	Krzysztof Kolasa <kkolasa@...soft.pl>
To:	Greg KH <gregkh@...uxfoundation.org>,
	Alexander Kuleshov <alex0xax@...il.com>
Cc:	dsterba@...e.cz, tom.yeon@...driver.com,
	linux-kernel@...r.kernel.org
Subject: Re: lz4: fix system halted at boot kernel x86_64 compressed lz4

On 03.04.2015 16:23, Greg KH wrote:
> On Fri, Apr 03, 2015 at 08:17:40PM +0600, Alexander Kuleshov wrote:
>> On 3 April 2015 at 19:58, Krzysztof Kolasa <kkolasa@...soft.pl> wrote:
>>> I do not believe that only I have a problem with the 64-bit kernel compressed in lz4.
>> Hello all,
>>
>> I can confirm that the same problem occurs for me. Tested current
>> mainline kernel with the Krzysztof's patch on qemu and real hardware,
>> it solves the problem.
> Ok, can someone send me the updated patch in a format that I can apply
> it in?  Please add your tested-by line to the patch as well.
>
> thanks,
>
> greg k-h
>


[PATCHv2] lz4: fix system halted at boot kernel x86_64 compressed lz4

Decompression process ends with an error when loading 64bit lz4 kernel:

Decoding failed
 
    -- System halted

This condition is not needed for 64bit kernel ( from the last commit d5e7caf )

if( ... ||
    (op + COPYLENGTH) > oend)
    goto _output_error

macro LZ4_SECURE_COPY() tests op and does not copy any data
when op exceeds the value, decompression process is continued.

added by analogy to lz4_uncompress_unknownoutputsize(...)

Signed-off-by: Krzysztof Kolasa <kkolasa@...soft.pl>
---
 lib/lz4/lz4_decompress.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c
index f0f5c5c..8a742b1 100644
--- a/lib/lz4/lz4_decompress.c
+++ b/lib/lz4/lz4_decompress.c
@@ -139,8 +139,12 @@ static int lz4_uncompress(const char *source, char *dest, int osize)
             /* Error: request to write beyond destination buffer */
             if (cpy > oend)
                 goto _output_error;
+#if LZ4_ARCH64
+            if ((ref + COPYLENGTH) > oend)
+#else
             if ((ref + COPYLENGTH) > oend ||
                     (op + COPYLENGTH) > oend)
+#endif
                 goto _output_error;
             LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
             while (op < cpy)
@@ -270,7 +274,13 @@ static int lz4_uncompress_unknownoutputsize(const char *source, char *dest,
         if (cpy > oend - COPYLENGTH) {
             if (cpy > oend)
                 goto _output_error; /* write outside of buf */
-
+#if LZ4_ARCH64
+            if ((ref + COPYLENGTH) > oend)
+#else
+            if ((ref + COPYLENGTH) > oend ||
+                    (op + COPYLENGTH) > oend)
+#endif
+                goto _output_error;
             LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
             while (op < cpy)
                 *op++ = *ref++;
-- 2.4.0.rc0.dirty

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