From: Nathan Lynch <nath...@linux.ibm.com> [ Upstream commit 0974d03eb479384466d828d65637814bee6b26d7 ]
Smatch warns: arch/powerpc/kernel/rtas.c:1932 __do_sys_rtas() warn: potential spectre issue 'args.args' [r] (local cap) The 'nargs' and 'nret' locals come directly from a user-supplied buffer and are used as indexes into a small stack-based array and as inputs to copy_to_user() after they are subject to bounds checks. Use array_index_nospec() after the bounds checks to clamp these values for speculative execution. Signed-off-by: Nathan Lynch <nath...@linux.ibm.com> Reported-by: Breno Leitao <lei...@debian.org> Reviewed-by: Breno Leitao <lei...@debian.org> Signed-off-by: Michael Ellerman <m...@ellerman.id.au> Link: https://msgid.link/20240530-sys_rtas-nargs-nret-v1-1-129acddd4...@linux.ibm.com [Minor context change fixed] Signed-off-by: Cliff Liu <donghua....@windriver.com> Signed-off-by: He Zhe <zhe...@windriver.com> --- Verified the powerpc build test. --- arch/powerpc/kernel/rtas.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 46b9476d7582..dc294c95da21 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -18,6 +18,7 @@ #include <linux/kernel.h> #include <linux/lockdep.h> #include <linux/memblock.h> +#include <linux/nospec.h> #include <linux/of.h> #include <linux/of_fdt.h> #include <linux/reboot.h> @@ -1839,6 +1840,9 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs) || nargs + nret > ARRAY_SIZE(args.args)) return -EINVAL; + nargs = array_index_nospec(nargs, ARRAY_SIZE(args.args)); + nret = array_index_nospec(nret, ARRAY_SIZE(args.args) - nargs); + /* Copy in args. */ if (copy_from_user(args.args, uargs->args, nargs * sizeof(rtas_arg_t)) != 0) -- 2.34.1
