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Subject[PATCH] sctp: use GFP_USER for user-controlled kmalloc
Date
Dmitry Vyukov reported that the user could trigger a kernel warning by
using a large len value for getsockopt SCTP_GET_LOCAL_ADDRS, as that
value directly affects the value used as a kmalloc() parameter.

This patch thus switches the allocation flags from all user-controllable
kmalloc size to GFP_USER to put some more restrictions on it and also
disables the warn, as they are not necessary.

Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
---
net/sctp/socket.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 897c01c029cab3d5805cc56b0964c70e06f4143a..676b3bb092e16848fd1c822e1c999af4a2ef198d 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -972,7 +972,7 @@ static int sctp_setsockopt_bindx(struct sock *sk,
return -EFAULT;

/* Alloc space for the address array in kernel memory. */
- kaddrs = kmalloc(addrs_size, GFP_KERNEL);
+ kaddrs = kmalloc(addrs_size, GFP_USER | __GFP_NOWARN);
if (unlikely(!kaddrs))
return -ENOMEM;

@@ -4928,7 +4928,7 @@ static int sctp_getsockopt_local_addrs(struct sock *sk, int len,
to = optval + offsetof(struct sctp_getaddrs, addrs);
space_left = len - offsetof(struct sctp_getaddrs, addrs);

- addrs = kmalloc(space_left, GFP_KERNEL);
+ addrs = kmalloc(space_left, GFP_USER | __GFP_NOWARN);
if (!addrs)
return -ENOMEM;

--
2.5.0


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