The functions grub_util_exec_pipe() and grub_util_exec_pipe_stderr()
currently call execvp(). If the call fails for any reason, the child
currently calls exit(127). This in turn executes the parents
atexit() handlers from the forked child, and then the same handlers
are called again from parent. This is usually not desired, and can
lead to deadlocks, and undesired behavior. So, change the exit() calls
to _exit() calls to avoid calling atexit() handlers from child.
Fixes: e75cf4a58 (unix exec: avoid atexit handlers when child exits)
Signed-off-by: Dimitri John Ledkov <xnox@ubuntu.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Commit 32ddc42c (efi: Only register shim_lock verifier if shim_lock
protocol is found and SB enabled) reintroduced CVE-2020-15705 which
previously only existed in the out-of-tree linuxefi patches and was
fixed as part of the BootHole patch series.
Under Secure Boot enforce loading shim_lock verifier. Allow skipping
shim_lock verifier if SecureBoot/MokSBState EFI variables indicate
skipping validations, or if GRUB image is built with --disable-shim-lock.
Fixes: 132ddc42c (efi: Only register shim_lock verifier if shim_lock
protocol is found and SB enabled)
Fixes: CVE-2020-15705
Fixes: CVE-2021-3418
Reported-by: Dimitri John Ledkov <xnox@ubuntu.com>
Signed-off-by: Dimitri John Ledkov <xnox@ubuntu.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Dimitri John Ledkov