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authorAndy Grover <andy.grover@oracle.com>2010-10-28 15:40:59 +0000
committerDavid S. Miller <davem@davemloft.net>2010-10-30 16:34:18 -0700
commitd139ff0907dac9ef72fb2cf301e345bac3aec42f (patch)
tree0ba63235a10b7640bc8b613da0d0cda220a55087 /net/rds/message.c
parentfc8162e3c034af743d8def435fda6396603d321f (diff)
downloadlinux-2.6.38-lt-ux500-d139ff0907dac9ef72fb2cf301e345bac3aec42f.tar.gz
RDS: Let rds_message_alloc_sgs() return NULL
Even with the previous fix, we still are reading the iovecs once to determine SGs needed, and then again later on. Preallocating space for sg lists as part of rds_message seemed like a good idea but it might be better to not do this. While working to redo that code, this patch attempts to protect against userspace rewriting the rds_iovec array between the first and second accesses. The consequences of this would be either a too-small or too-large sg list array. Too large is not an issue. This patch changes all callers of message_alloc_sgs to handle running out of preallocated sgs, and fail gracefully. Signed-off-by: Andy Grover <andy.grover@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rds/message.c')
-rw-r--r--net/rds/message.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/net/rds/message.c b/net/rds/message.c
index a84545dae37..848cff45183 100644
--- a/net/rds/message.c
+++ b/net/rds/message.c
@@ -224,6 +224,9 @@ struct scatterlist *rds_message_alloc_sgs(struct rds_message *rm, int nents)
WARN_ON(rm->m_used_sgs + nents > rm->m_total_sgs);
WARN_ON(!nents);
+ if (rm->m_used_sgs + nents > rm->m_total_sgs)
+ return NULL;
+
sg_ret = &sg_first[rm->m_used_sgs];
sg_init_table(sg_ret, nents);
rm->m_used_sgs += nents;
@@ -246,6 +249,8 @@ struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned in
rm->m_inc.i_hdr.h_len = cpu_to_be32(total_len);
rm->data.op_nents = ceil(total_len, PAGE_SIZE);
rm->data.op_sg = rds_message_alloc_sgs(rm, num_sgs);
+ if (!rm->data.op_sg)
+ return ERR_PTR(-ENOMEM);
for (i = 0; i < rm->data.op_nents; ++i) {
sg_set_page(&rm->data.op_sg[i],