Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ca2a05aa7c72309ee65164c78fa2be7a5038215e
Commit: ca2a05aa7c72309ee65164c78fa2be7a5038215e
Parent: a490c681cbcf65d548138c377bb691c85824d323
Author: J. Bruce Fields <[EMAIL PROTECTED]>
AuthorDate: Sun Nov 11 15:43:12 2007 -0500
Committer: J. Bruce Fields <[EMAIL PROTECTED]>
CommitDate: Fri Feb 1 16:42:03 2008 -0500
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 <[EMAIL PROTECTED]>
---
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 5733394..bf1e792 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]);
-
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