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authorFlorent Revest <revest@chromium.org>2023-08-28 18:08:56 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-10-07 00:44:11 +0300
commit0da668333fb07805c2836d5d50e26eda915b24a1 (patch)
tree986eebdba7bbe38df9931e2c81e819cdbeb03d10 /tools
parentc93d05a729f9646a38aaf53781b447c99cfd86fb (diff)
downloadlinux-0da668333fb07805c2836d5d50e26eda915b24a1.tar.xz
mm: make PR_MDWE_REFUSE_EXEC_GAIN an unsigned long
Defining a prctl flag as an int is a footgun because on a 64 bit machine and with a variadic implementation of prctl (like in musl and glibc), when used directly as a prctl argument, it can get casted to long with garbage upper bits which would result in unexpected behaviors. This patch changes the constant to an unsigned long to eliminate that possibilities. This does not break UAPI. I think that a stable backport would be "nice to have": to reduce the chances that users build binaries that could end up with garbage bits in their MDWE prctl arguments. We are not aware of anyone having yet encountered this corner case with MDWE prctls but a backport would reduce the likelihood it happens, since this sort of issues has happened with other prctls. But If this is perceived as a backporting burden, I suppose we could also live without a stable backport. Link: https://lkml.kernel.org/r/20230828150858.393570-5-revest@chromium.org Fixes: b507808ebce2 ("mm: implement memory-deny-write-execute as a prctl") Signed-off-by: Florent Revest <revest@chromium.org> Suggested-by: Alexey Izbyshev <izbyshev@ispras.ru> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Ayush Jain <ayush.jain3@amd.com> Cc: Greg Thelen <gthelen@google.com> Cc: Joey Gouly <joey.gouly@arm.com> Cc: KP Singh <kpsingh@kernel.org> Cc: Mark Brown <broonie@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Peter Xu <peterx@redhat.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Szabolcs Nagy <Szabolcs.Nagy@arm.com> Cc: Topi Miettinen <toiwoton@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'tools')
-rw-r--r--tools/include/uapi/linux/prctl.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/include/uapi/linux/prctl.h b/tools/include/uapi/linux/prctl.h
index 3c36aeade991..9a85c69782bd 100644
--- a/tools/include/uapi/linux/prctl.h
+++ b/tools/include/uapi/linux/prctl.h
@@ -283,7 +283,7 @@ struct prctl_mm_map {
/* Memory deny write / execute */
#define PR_SET_MDWE 65
-# define PR_MDWE_REFUSE_EXEC_GAIN 1
+# define PR_MDWE_REFUSE_EXEC_GAIN (1UL << 0)
#define PR_GET_MDWE 66