linux-kernel - [PATCH 5.11 062/120] RISC-V: Fix out-of-bounds accesses in init

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Date:   Mon, 22 Mar 2021 13:27:25 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Geert Uytterhoeven <geert@...ux-m68k.org>,
        Atish Patra <atish.patra@....com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>
Subject: [PATCH 5.11 062/120] RISC-V: Fix out-of-bounds accesses in init_resources()

From: Geert Uytterhoeven <geert@...ux-m68k.org>

commit ce989f1472ae350e844b10c880b22543168fbc92 upstream.

init_resources() allocates an array of resources, based on the current
total number of memory regions and reserved memory regions.  However,
allocating this array using memblock_alloc() might increase the number
of reserved memory regions.  If that happens, populating the array later
based on the new number of regions will cause out-of-bounds writes
beyond the end of the allocated array.

Fix this by allocating one more entry, which may or may not be used.

Fixes: 797f0375dd2ef5cd ("RISC-V: Do not allocate memblock while iterating reserved memblocks")
Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Reviewed-by: Atish Patra <atish.patra@....com>
Cc: stable@...r.kernel.org
Signed-off-by: Palmer Dabbelt <palmerdabbelt@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/riscv/kernel/setup.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -147,7 +147,8 @@ static void __init init_resources(void)
 	bss_res.end = __pa_symbol(__bss_stop) - 1;
 	bss_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
 
-	mem_res_sz = (memblock.memory.cnt + memblock.reserved.cnt) * sizeof(*mem_res);
+	/* + 1 as memblock_alloc() might increase memblock.reserved.cnt */
+	mem_res_sz = (memblock.memory.cnt + memblock.reserved.cnt + 1) * sizeof(*mem_res);
 	mem_res = memblock_alloc(mem_res_sz, SMP_CACHE_BYTES);
 	if (!mem_res)
 		panic("%s: Failed to allocate %zu bytes\n", __func__, mem_res_sz);