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| author | Nathan Lynch <nathanl@linux.ibm.com> | 2024-05-30 19:44:12 -0500 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2024-06-28 22:28:58 +1000 |
| commit | 0974d03eb479384466d828d65637814bee6b26d7 (patch) | |
| tree | 9e61fa2740cb95cd3bb6a215534c526c025724a2 | |
| parent | d5d1a1a55a7f227c0f41847b0598982f0a93170d (diff) | |
| download | linux-stable-0974d03eb479384466d828d65637814bee6b26d7.tar.gz linux-stable-0974d03eb479384466d828d65637814bee6b26d7.tar.bz2 linux-stable-0974d03eb479384466d828d65637814bee6b26d7.zip | |
powerpc/rtas: Prevent Spectre v1 gadget construction in sys_rtas()
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.com
| -rw-r--r-- | arch/powerpc/kernel/rtas.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 8064d9c3de86..f7e86e09c49f 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -19,6 +19,7 @@ #include <linux/lockdep.h> #include <linux/memblock.h> #include <linux/mutex.h> +#include <linux/nospec.h> #include <linux/of.h> #include <linux/of_fdt.h> #include <linux/reboot.h> @@ -1916,6 +1917,9 @@ 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) |