From 7792ee8b37d7be90ffa4b28f1ed24908a6921601 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Mon, 21 Jan 2019 16:55:33 +0800 Subject: [PATCH] efi: Permit calling efi_mem_reserve_persistent() from atomic context mainline inclusion from mainline-4.20 commit 63eb322d89c8505af9b4a3d703e85e42281ebaa0 category: bugfix bugzilla: 5501 CVE: NA ------------------------------------------------- Currently, efi_mem_reserve_persistent() may not be called from atomic context, since both the kmalloc() call and the memremap() call may sleep. The kmalloc() call is easy enough to fix, but the memremap() call needs to be moved into an init hook since we cannot control the memory allocation behavior of memremap() at the call site. Signed-off-by: Ard Biesheuvel Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20181114175544.12860-6-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar Signed-off-by: Yang Yingliang Reviewed-by: Hanjun Guo --- drivers/firmware/efi/efi.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 72a4da76d274..fad7c62cfc0e 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -967,36 +967,43 @@ bool efi_is_table_address(unsigned long phys_addr) } static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock); +static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init; int efi_mem_reserve_persistent(phys_addr_t addr, u64 size) { - struct linux_efi_memreserve *rsv, *parent; + struct linux_efi_memreserve *rsv; - if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR) + if (!efi_memreserve_root) return -ENODEV; - rsv = kmalloc(sizeof(*rsv), GFP_KERNEL); + rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC); if (!rsv) return -ENOMEM; - parent = memremap(efi.mem_reserve, sizeof(*rsv), MEMREMAP_WB); - if (!parent) { - kfree(rsv); - return -ENOMEM; - } - rsv->base = addr; rsv->size = size; spin_lock(&efi_mem_reserve_persistent_lock); - rsv->next = parent->next; - parent->next = __pa(rsv); + rsv->next = efi_memreserve_root->next; + efi_memreserve_root->next = __pa(rsv); spin_unlock(&efi_mem_reserve_persistent_lock); - memunmap(parent); + return 0; +} +static int __init efi_memreserve_root_init(void) +{ + if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR) + return -ENODEV; + + efi_memreserve_root = memremap(efi.mem_reserve, + sizeof(*efi_memreserve_root), + MEMREMAP_WB); + if (!efi_memreserve_root) + return -ENOMEM; return 0; } +early_initcall(efi_memreserve_root_init); #ifdef CONFIG_KEXEC static int update_efi_random_seed(struct notifier_block *nb, -- GitLab