mainline inclusion from mainline-v6.11-rc1 commit 0974d03eb479384466d828d65637814bee6b26d7 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IARWPW CVE: CVE-2024-46774

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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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 nathanl@linux.ibm.com Reported-by: Breno Leitao leitao@debian.org Reviewed-by: Breno Leitao leitao@debian.org Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://msgid.link/20240530-sys_rtas-nargs-nret-v1-1-129acddd4d89@linux.ibm.... Conflicts: arch/powerpc/kernel/rtas.c [Some header files are not included.] Signed-off-by: Bowen You youbowen2@huawei.com --- 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 5976a25c6264..9d87e7dec5f1 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -21,6 +21,7 @@ #include <linux/completion.h> #include <linux/cpumask.h> #include <linux/memblock.h> +#include <linux/nospec.h> #include <linux/slab.h> #include <linux/reboot.h> #include <linux/syscalls.h> @@ -1173,6 +1174,9 @@ 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)