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authorBenny Halevy <bhalevy@panasas.com>2008-05-29 12:56:08 +0300
committerJ. Bruce Fields <bfields@citi.umich.edu>2008-06-23 13:02:48 -0400
commit13b1867cacbfe6d8203f432996bd8a2ee6b04e79 (patch)
tree04c3a0f519f7115073f7b0ca10b5e15669d88515
parent3b12cd9862d5f560031d90bda78952ab55e36b24 (diff)
nfsd: make nfs4xdr WRITEMEM safe against zero count
WRITEMEM zeroes the last word in the destination buffer for padding purposes, but this must not be done if no bytes are to be copied, as it would result in zeroing of the word right before the array. The current implementation works since it's always called with non zero nbytes or it follows an encoding of the string (or opaque) length which, if equal to zero, can be overwritten with zero. Nevertheless, it seems safer to check for this case. Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
-rw-r--r--fs/nfsd/nfs4xdr.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index c513bbdf2d3..9547ab63627 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1201,7 +1201,7 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
*p++ = htonl((u32)((n) >> 32)); \
*p++ = htonl((u32)(n)); \
} while (0)
-#define WRITEMEM(ptr,nbytes) do { \
+#define WRITEMEM(ptr,nbytes) do if (nbytes > 0) { \
*(p + XDR_QUADLEN(nbytes) -1) = 0; \
memcpy(p, ptr, nbytes); \
p += XDR_QUADLEN(nbytes); \