CVE-2025-21872
efi: Don't map the entire mokvar table to determine its size
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efi: Don't map the entire mokvar table to determine its size
In the Linux kernel, the following vulnerability has been resolved: efi: Don't map the entire mokvar table to determine its size Currently, when validating the mokvar table, we (re)map the entire table on each iteration of the loop, adding space as we discover new entries. If the table grows over a certain size, this fails due to limitations of early_memmap(), and we get a failure and traceback: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at mm/early_ioremap.c:139 __early_ioremap+0xef/0x220 ... Call Trace: <TASK> ? __early_ioremap+0xef/0x220 ? __warn.cold+0x93/0xfa ? __early_ioremap+0xef/0x220 ? report_bug+0xff/0x140 ? early_fixup_exception+0x5d/0xb0 ? early_idt_handler_common+0x2f/0x3a ? __early_ioremap+0xef/0x220 ? efi_mokvar_table_init+0xce/0x1d0 ? setup_arch+0x864/0xc10 ? start_kernel+0x6b/0xa10 ? x86_64_start_reservations+0x24/0x30 ? x86_64_start_kernel+0xed/0xf0 ? common_startup_64+0x13e/0x141 </TASK> ---[ end trace 0000000000000000 ]--- mokvar: Failed to map EFI MOKvar config table pa=0x7c4c3000, size=265187. Mapping the entire structure isn't actually necessary, as we don't ever need more than one entry header mapped at once. Changes efi_mokvar_table_init() to only map each entry header, not the entire table, when determining the table size. Since we're not mapping any data past the variable name, it also changes the code to enforce that each variable name is NUL terminated, rather than attempting to verify it in place.
Reserved 2024-12-29 | Published 2025-03-27 | Updated 2025-05-10 | Assigner Linuxgit.kernel.org/...c/46c0454ffb78ce9d3355a3cccac86383ea8ddd55
git.kernel.org/...c/ea3f0b362dfe4ef885ef812bfaf4088176422c91
git.kernel.org/...c/65f4aebb8127708ba668dd938e83b8558abfc5cd
git.kernel.org/...c/97bd560b6cc4c26386a53b4881bf03e96f9ba03a
git.kernel.org/...c/2b90e7ace79774a3540ce569e000388f8d22c9e0
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