c2cae77abe
A NULL pointer dereference can occur in grub_net_udp_close(data->sock) when handling a malformed TFTP OACK packet. This issue was discovered via fuzzing. When a malformed OACK packet contains an invalid file size, "tsize", value tftp_receive() detects the error and saves it via grub_error_save(&data->save_err). Later, tftp_open() restores this error and calls grub_net_udp_close(data->sock) assuming the socket is still valid. However, the socket may have already been closed and set to NULL after processing the final data block in tftp_receive() leading to a NULL pointer dereference when attempting to close it again. Fix it by checking if the socket is non-NULL before closing. Signed-off-by: Lidong Chen <lidong.chen@oracle.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> Reviewed-by: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
This is GRUB 2, the second version of the GRand Unified Bootloader. GRUB 2 is rewritten from scratch to make GNU GRUB cleaner, safer, more robust, more powerful, and more portable. See the file NEWS for a description of recent changes to GRUB 2. See the file INSTALL for instructions on how to build and install the GRUB 2 data and program files. See the file MAINTAINERS for information about the GRUB maintainers, etc. If you found a security vulnerability in the GRUB please check the SECURITY file to get more information how to properly report this kind of bugs to the maintainers. Please visit the official web page of GRUB 2, for more information. The URL is <http://www.gnu.org/software/grub/grub.html>. More extensive documentation is available in the Info manual, accessible using 'info grub' after building and installing GRUB 2. There are a number of important user-visible differences from the first version of GRUB, now known as GRUB Legacy. For a summary, please see: info grub Introduction 'Changes from GRUB Legacy'