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efirtc: Pass a dummy tmcap pointer to efi_get_time_locked

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As noted in the comment, UEFI spec claims the capabilities pointer is
optional, but some implementations will choke and attempt to dereference it
without checking. This specific problem was found on a Lenovo Thinkpad X220
that would panic in efirtc_identify.
This commit is contained in:
Kyle Evans 2018-03-13 15:01:23 +00:00
parent b7feabf906
commit 8521b4a9df
1 changed files with 8 additions and 1 deletions
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9
sys/dev/efidev/efirt.c
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@ -259,12 +259,19 @@ efi_get_time_locked(struct efi_tm *tm, struct efi_tmcap *tmcap)
int
efi_get_time(struct efi_tm *tm)
{
struct efi_tmcap dummy;
int error;
if (efi_runtime == NULL)
return (ENXIO);
EFI_TIME_LOCK()
error = efi_get_time_locked(tm, NULL);
/*
* UEFI spec states that the Capabilities argument to GetTime is
* optional, but some UEFI implementations choke when passed a NULL
* pointer. Pass a dummy efi_dmcap, even though we won't use it,
* to workaround such implementations.
*/
error = efi_get_time_locked(tm, &dummy);
EFI_TIME_UNLOCK()
return (error);
}