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block/nfs: limit maximum readahead size to 1MB 

a malicious caller could otherwise specify a very
large value via the URI and force libnfs to allocate
a large amount of memory for the readahead buffer.

Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Lieven <pl@kamp.de>
Message-id: 1435317241-25585-1-git-send-email-pl@kamp.de
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Peter Lieven 2015-06-26 13:14:01 +02:00 committed by Stefan Hajnoczi
parent 9049736ec7
commit 29c838cdc9
1 changed files with 7 additions and 0 deletions
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7
block/nfs.c
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@ -35,6 +35,8 @@
#include "sysemu/sysemu.h"
#include <nfsc/libnfs.h>
#define QEMU_NFS_MAX_READAHEAD_SIZE 1048576
typedef struct NFSClient {
struct nfs_context *context;
struct nfsfh *fh;
@ -327,6 +329,11 @@ static int64_t nfs_client_open(NFSClient *client, const char *filename,
nfs_set_tcp_syncnt(client->context, val);
#ifdef LIBNFS_FEATURE_READAHEAD
} else if (!strcmp(qp->p[i].name, "readahead")) {
if (val > QEMU_NFS_MAX_READAHEAD_SIZE) {
error_report("NFS Warning: Truncating NFS readahead"
" size to %d", QEMU_NFS_MAX_READAHEAD_SIZE);
val = QEMU_NFS_MAX_READAHEAD_SIZE;
}
nfs_set_readahead(client->context, val);
#endif
} else {