From b1a156d86f55a8fa3f78ece5bee7748ec75e7b82 Mon Sep 17 00:00:00 2001 From: John Levon Date: Mon, 19 Aug 2024 11:44:36 +0100 Subject: [PATCH] Add further sanity checking of hdr->error_no (#805) >>> CID 467267: Insecure data handling (INTEGER_OVERFLOW) >>> The cast of "hdr->error_no" to a signed type could result in a negative number. Indeed, if a client sends a very large ->error_no, this could end up with a negative errno value. This doesn't seem like an issue, but nonetheless tighten up our validation. For some reason Coverity only complained about tran_pipe.c, but the same problem exists in tran_sock.c. Signed-off-by: John Levon --- lib/private.h | 6 ++++++ lib/tran_pipe.c | 2 +- lib/tran_sock.c | 2 +- 3 files changed, 8 insertions(+), 2 deletions(-) diff --git a/lib/private.h b/lib/private.h index e3d97b32..b89df8b2 100644 --- a/lib/private.h +++ b/lib/private.h @@ -61,6 +61,12 @@ sizeof(struct vfio_user_header) + \ sizeof(struct vfio_user_region_access)) +/* + * Maximum value we are prepared to accept in hdr->error_no. Somewhat arbitrary + * value low enough to avoid any signed conversion issues. + */ +#define SERVER_MAX_ERROR_NO (4096) + /* * Structure used to hold an in-flight request+reply. * diff --git a/lib/tran_pipe.c b/lib/tran_pipe.c index 4c3dc9c1..48d8ea4e 100644 --- a/lib/tran_pipe.c +++ b/lib/tran_pipe.c @@ -137,7 +137,7 @@ tran_pipe_recv(int fd, struct vfio_user_header *hdr, bool is_reply, } if (hdr->flags & VFIO_USER_F_ERROR) { - if (hdr->error_no <= 0) { + if (hdr->error_no <= 0 || hdr->error_no > SERVER_MAX_ERROR_NO) { hdr->error_no = EINVAL; } return ERROR_INT(hdr->error_no); diff --git a/lib/tran_sock.c b/lib/tran_sock.c index 024e5b01..5f144b29 100644 --- a/lib/tran_sock.c +++ b/lib/tran_sock.c @@ -217,7 +217,7 @@ tran_sock_recv_fds(int sock, struct vfio_user_header *hdr, bool is_reply, } if (hdr->flags & VFIO_USER_F_ERROR) { - if (hdr->error_no <= 0) { + if (hdr->error_no <= 0 || hdr->error_no > SERVER_MAX_ERROR_NO) { hdr->error_no = EINVAL; } return ERROR_INT(hdr->error_no);