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FAILED: patch "[PATCH] efi: READ_ONCE rng seed size before munmap" failed to apply to 4.19-stable tree

PATCH [email protected] 1 participant 1 message Mar 10, 2020

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The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From be36f9e7517e17810ec369626a128d7948942259 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <[email protected]>
Date: Fri, 21 Feb 2020 09:48:49 +0100
Subject: [PATCH] efi: READ_ONCE rng seed size before munmap

This function is consistent with using size instead of seed->size (except for one place that this patch fixes), but it reads seed->size without using READ_ONCE, which means the compiler might still do something unwanted. So, this commit simply adds the READ_ONCE wrapper.

Fixes 636259880a7e ("efi: Add support for seeding the RNG from a UEFI ...")
Signed-off-by Jason A. Donenfeld <[email protected]>
Signed-off-by Ard Biesheuvel <[email protected]>
Signed-off-by Ingo Molnar <[email protected]>
Cc [email protected]
Cc Ingo Molnar <[email protected]>
Cc Thomas Gleixner <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Link https://lore.kernel.org/r/[email protected] open here
drivers/firmware/efi/efi.c +2 -2
index 621220ab3d0e..21ea99f65113 100644
@@ -552,7 +552,7 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz,
 
 		seed = early_memremap(efi.rng_seed, sizeof(*seed));
 		if (seed != NULL) {
-			size = seed->size;
+			size = READ_ONCE(seed->size);
 			early_memunmap(seed, sizeof(*seed));
 		} else {
 			pr_err("Could not map UEFI random seed!\n");

@@ -562,7 +562,7 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz,
 					      sizeof(*seed) + size);
 			if (seed != NULL) {
 				pr_notice("seeding entropy pool\n");
-				add_bootloader_randomness(seed->bits, seed->size);
+				add_bootloader_randomness(seed->bits, size);
 				early_memunmap(seed, sizeof(*seed) + size);
 			} else {
 				pr_err("Could not map UEFI random seed!\n");