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| author | J. Bruce Fields <bfields@citi.umich.edu> | 2007-11-11 15:43:12 -0500 |
|---|---|---|
| committer | J. Bruce Fields <bfields@citi.umich.edu> | 2008-02-01 16:42:03 -0500 |
| commit | ca2a05aa7c72309ee65164c78fa2be7a5038215e (patch) | |
| tree | f362d7c14652dfea0d93508007f8fc87d10d6980 /fs/nfsd/nfs4xdr.c | |
| parent | a490c681cbcf65d548138c377bb691c85824d323 (diff) | |
| download | linux-ca2a05aa7c72309ee65164c78fa2be7a5038215e.tar.bz2 | |
nfsd: Fix handling of negative lengths in read_buf()
The length "nbytes" passed into read_buf should never be negative, but
we check only for too-large values of "nbytes", not for too-small
values. Make nbytes unsigned, so it's clear that the former tests are
sufficient. (Despite this read_buf() currently correctly returns an xdr
error in the case of a negative length, thanks to an unsigned
comparison with size_of() and bounds-checking in kmalloc(). This seems
very fragile, though.)
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Diffstat (limited to 'fs/nfsd/nfs4xdr.c')
| -rw-r--r-- | fs/nfsd/nfs4xdr.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 57333944af7f..bf1e792a65a0 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -148,12 +148,12 @@ xdr_error: \ } \ } while (0) -static __be32 *read_buf(struct nfsd4_compoundargs *argp, int nbytes) +static __be32 *read_buf(struct nfsd4_compoundargs *argp, u32 nbytes) { /* We want more bytes than seem to be available. * Maybe we need a new page, maybe we have just run out */ - int avail = (char*)argp->end - (char*)argp->p; + unsigned int avail = (char *)argp->end - (char *)argp->p; __be32 *p; if (avail + argp->pagelen < nbytes) return NULL; @@ -169,6 +169,11 @@ static __be32 *read_buf(struct nfsd4_compoundargs *argp, int nbytes) return NULL; } + /* + * The following memcpy is safe because read_buf is always + * called with nbytes > avail, and the two cases above both + * guarantee p points to at least nbytes bytes. + */ memcpy(p, argp->p, avail); /* step to next page */ argp->p = page_address(argp->pagelist[0]); |