[ 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
033ef338b6 ("powerpc: Merge rtas.c into arch/powerpc/kernel"); the
old ppc64 version of this code did not have this problem.
Use memmove() instead.
Fixes: 033ef338b6 ("powerpc: Merge rtas.c into arch/powerpc/kernel")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230220-rtas-queue-for-6-4-v1-2-010e4416f13f@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
c5a6526711