Fix stack buffer overflow in net functions with large file descriptor

Fix a stack buffer overflow with mbedtls_net_recv_timeout() when given a
file descriptor that is beyond FD_SETSIZE. The bug was due to not checking
that the file descriptor is within the range of an fd_set object.

Fix #4169

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2021-02-24 19:49:44 +01:00
parent 9c1ae18c9c
commit 33d816aff9
2 changed files with 10 additions and 0 deletions

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@ -0,0 +1,3 @@
Security
* Fix a stack buffer overflow with mbedtls_net_recv_timeout() when given a
file descriptor that is beyond FD_SETSIZE. Reported by FigBug in #4169.

View File

@ -535,6 +535,13 @@ int mbedtls_net_recv_timeout( void *ctx, unsigned char *buf, size_t len,
if( fd < 0 )
return( MBEDTLS_ERR_NET_INVALID_CONTEXT );
/* A limitation of select() is that it only works with file descriptors
* up to FD_SETSIZE. This is a limitation of the fd_set type. Error out
* early, because attempting to call FD_SET on a large file descriptor
* is a buffer overflow on typical platforms. */
if( fd >= FD_SETSIZE )
return( MBEDTLS_ERR_NET_RECV_FAILED );
FD_ZERO( &read_fds );
FD_SET( fd, &read_fds );