[Xen-changelog] [xen stable-4.12] lz4: fix system halt at boot kernel on x86_64

[patchbot@xxxxxxx]

commit 8f333d13917cbd66b655df18a4476ed58df9d16f
Author:     Krzysztof Kolasa <kkolasa@xxxxxxxxxx>
AuthorDate: Wed Dec 11 15:15:52 2019 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Dec 11 15:15:52 2019 +0100

    lz4: fix system halt at boot kernel on x86_64
    
    Sometimes, on x86_64, decompression fails with the following
    error:
    
    Decompressing Linux...
    
    Decoding failed
    
     -- System halted
    
    This condition is not needed for a 64bit kernel(from 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.
    
    added by analogy to lz4_uncompress_unknownoutputsize(...)
    
    Signed-off-by: Krzysztof Kolasa <kkolasa@xxxxxxxxxx>
    [Linux commit 99b7e93c95c78952724a9783de6c78def8fbfc3f]
    
    The offending commit in our case is fcc17f96c277 ("LZ4 : fix the data
    abort issue").
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: 5d90ff79542ab9c6eebe5c315c68c196bcf353b9
    master date: 2019-12-09 14:02:35 +0100
---
 xen/common/lz4/decompress.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/xen/common/lz4/decompress.c b/xen/common/lz4/decompress.c
index e8636e193a..bef3a9a99c 100644
--- a/xen/common/lz4/decompress.c
+++ b/xen/common/lz4/decompress.c
@@ -132,8 +132,12 @@ static int INIT lz4_uncompress(const unsigned char 
*source, unsigned char *dest,
                        /* 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)
@@ -266,7 +270,13 @@ static int lz4_uncompress_unknownoutputsize(const unsigned 
char *source,
                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++;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.12

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