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| author | Chuck Lever <chuck.lever@oracle.com> | 2026-05-26 13:34:54 -0400 |
|---|---|---|
| committer | Chuck Lever <cel@kernel.org> | 2026-07-27 08:49:57 -0400 |
| commit | 7ba49e2cca1f1b71b672c28e9f494f9f570d3295 (patch) | |
| tree | 8466d62279b90529c9525357dd6b8060d090ce1b /net/sunrpc | |
| parent | fa183d59e531e016d4495e21f00d80c63aebd907 (diff) | |
| download | linux-next-7ba49e2cca1f1b71b672c28e9f494f9f570d3295.tar.gz linux-next-7ba49e2cca1f1b71b672c28e9f494f9f570d3295.zip | |
svcrdma: Reject Read lists that exceed the page budget
Individual Read segment lengths are validated at decode time, but
nothing prevents a requester from sending multiple segments whose
cumulative length exceeds the rq_pages array budget. When one
segment fills the page array exactly, the runtime guard in
svc_rdma_build_read_segment() is bypassed because len reaches zero.
A subsequent segment then accesses the NULL sentinel slot at
rq_pages[rq_maxpages], resulting in a NULL pointer dereference during
DMA mapping.
Accumulate pages across all Read segments and reject the message at
decode time when the total would overflow the page budget.
Fixes: 026d958b38c6 ("svcrdma: Add recvfrom helpers to svc_rdma_rw.c")
Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'net/sunrpc')
| -rw-r--r-- | net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c index d64b5f78ce8a..fdfed1be97da 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -440,11 +440,14 @@ static void svc_rdma_build_arg_xdr(struct svc_rqst *rqstp, * to the first byte past the Read list. rc_read_pcl and * rc_call_pcl cl_count fields are set to the number of * Read segments in the list. - * %false: Read list is corrupt. @rctxt's xdr_stream is left in an - * unknown state. + * %false: Read list is corrupt or exceeds the page budget. @rctxt's + * xdr_stream is left in an unknown state. */ static bool xdr_count_read_segments(struct svc_rdma_recv_ctxt *rctxt, __be32 *p) { + unsigned int maxlen = rctxt->rc_maxpages << PAGE_SHIFT; + unsigned int total_len = 0; + rctxt->rc_call_pcl.cl_count = 0; rctxt->rc_read_pcl.cl_count = 0; while (xdr_item_is_present(p)) { @@ -458,7 +461,10 @@ static bool xdr_count_read_segments(struct svc_rdma_recv_ctxt *rctxt, __be32 *p) xdr_decode_read_segment(p, &position, &handle, &length, &offset); - if (length > rctxt->rc_maxpages << PAGE_SHIFT) + if (length > maxlen) + return false; + total_len += length; + if (PAGE_ALIGN(total_len) > maxlen) return false; if (position) { if (position & 3) |