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net/rds: restrict iovecs length for RDS_CMSG_RDMA_ARGS

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syzbot found WARNING in rds_rdma_extra_size [1] when RDS_CMSG_RDMA_ARGS
control message is passed with user-controlled
0x40001 bytes of args->nr_local, causing order >= MAX_ORDER condition.

The exact value 0x40001 can be checked with UIO_MAXIOV which is 0x400.
So for kcalloc() 0x400 iovecs with sizeof(struct rds_iovec) = 0x10
is the closest limit, with 0x10 leftover.

Same condition is currently done in rds_cmsg_rdma_args().

[1] WARNING: mm/page_alloc.c:5011
[..]
Call Trace:
 alloc_pages_current+0x18c/0x2a0 mm/mempolicy.c:2267
 alloc_pages include/linux/gfp.h:547 [inline]
 kmalloc_order+0x2e/0xb0 mm/slab_common.c:837
 kmalloc_order_trace+0x14/0x120 mm/slab_common.c:853
 kmalloc_array include/linux/slab.h:592 [inline]
 kcalloc include/linux/slab.h:621 [inline]
 rds_rdma_extra_size+0xb2/0x3b0 net/rds/rdma.c:568
 rds_rm_size net/rds/send.c:928 [inline]

Reported-by: syzbot+1bd2b07f93745fa38425@syzkaller.appspotmail.com
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Link: https://lore.kernel.org/r/20210201203233.1324704-1-snovitoll@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Sabyrzhan Tasbolatov 2021-02-02 02:32:33 +06:00 committed by Jakub Kicinski
parent 43f4a20a12
commit a11148e6fc
1 changed files with 3 additions and 0 deletions
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3
net/rds/rdma.c
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@ -565,6 +565,9 @@ int rds_rdma_extra_size(struct rds_rdma_args *args,
if (args->nr_local == 0)
return -EINVAL;
if (args->nr_local > UIO_MAXIOV)
return -EMSGSIZE;
iov->iov = kcalloc(args->nr_local,
sizeof(struct rds_iovec),
GFP_KERNEL);