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Commit ff3edfb3 authored by Nathan Lynch's avatar Nathan Lynch Committed by Greg Kroah-Hartman
Browse files

powerpc/rtas: use memmove for potentially overlapping buffer copy 



[ Upstream commit 271208ee5e335cb1ad280d22784940daf7ddf820 ]

Using memcpy() isn't safe when buf is identical to rtas_err_buf, which
can happen during boot before slab is up. Full context which may not
be obvious from the diff:

	if (altbuf) {
		buf = altbuf;
	} else {
		buf = rtas_err_buf;
		if (slab_is_available())
			buf = kmalloc(RTAS_ERROR_LOG_MAX, GFP_ATOMIC);
	}
	if (buf)
		memcpy(buf, rtas_err_buf, RTAS_ERROR_LOG_MAX);

This was found by inspection and I'm not aware of it causing problems
in practice. It appears to have been introduced by commit
033ef338 ("powerpc: Merge rtas.c into arch/powerpc/kernel"); the
old ppc64 version of this code did not have this problem.

Use memmove() instead.

Fixes: 033ef338 ("powerpc: Merge rtas.c into arch/powerpc/kernel")
Signed-off-by: default avatarNathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: default avatarAndrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230220-rtas-queue-for-6-4-v1-2-010e4416f13f@linux.ibm.com


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 333a2a98

arch/powerpc/kernel/rtas.c

+1 −1
Original line number Diff line number Diff line
@@ -398,7 +398,7 @@ static char *__fetch_rtas_last_error(char *altbuf) 
				buf = kmalloc(RTAS_ERROR_LOG_MAX, GFP_ATOMIC);

		}

		if (buf)

			memcpy(buf, rtas_err_buf, RTAS_ERROR_LOG_MAX);

			memmove(buf, rtas_err_buf, RTAS_ERROR_LOG_MAX);

	}



	return buf;