libseccomp: fix seccomp_export_bpf_mem out-of-bounds read

Fixes segfaults in ptests on musl
Failed ptests:
{'libseccomp': ['11-basic-basic_errors%%001-00001_11-basic-basic_errors_rc=139']}

(From OE-Core rev: 4f26edb6fd7e3dc5f81c56faed3a0edd9264bf66)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-support/libseccomp/files/0001-api-fix-seccomp_export_bpf_mem-out-of-bounds-read.patch

@@ -0,0 +1,37 @@
+From 83a56d74482ef6b6cc9311b14bf9ea23573f5d4e Mon Sep 17 00:00:00 2001
+From: Alyssa Ross <hi@alyssa.is>
+Date: Thu, 13 Feb 2025 12:05:17 +0100
+Subject: [PATCH] api: fix seccomp_export_bpf_mem out-of-bounds read
+
+*len is the length of the destination buffer, but program->blks is
+probably not anywhere near that long.  It's already been checked above
+that BPF_PGM_SIZE(program) is less than or equal to *len, so that's
+the correct value to use here to avoid either reading or writing too
+much.
+
+I noticed this because tests/11-basic-basic_errors started failing on
+musl after e797591 ("all: add seccomp_precompute() functionality").
+
+Upstream-Status: Backport [https://github.com/seccomp/libseccomp/commit/dd759e8c4f5685b526638fba9ec4fc24c37c9aec]
+Signed-off-by: Alyssa Ross <hi@alyssa.is>
+Acked-by: Tom Hromatka <tom.hromatka@oracle.com>
+Signed-off-by: Paul Moore <paul@paul-moore.com>
+(imported from commit e8dbc6b555fb936bdfb8ab86f9a45fda96a8b7a2)
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+---
+ src/api.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/api.c b/src/api.c
+index adccef3..65a277a 100644
+--- a/src/api.c
++++ b/src/api.c
+@@ -786,7 +786,7 @@ API int seccomp_export_bpf_mem(const scmp_filter_ctx ctx, void *buf,
+ 		if (BPF_PGM_SIZE(program) > *len)
+ 			rc = _rc_filter(-ERANGE);
+ 		else
+-			memcpy(buf, program->blks, *len);
++			memcpy(buf, program->blks, BPF_PGM_SIZE(program));
+ 	}
+ 	*len = BPF_PGM_SIZE(program);
+ 

meta/recipes-support/libseccomp/libseccomp_2.6.0.bb

@@ -10,6 +10,7 @@ DEPENDS += "gperf-native"
 SRCREV = "c7c0caed1d04292500ed4b9bb386566053eb9775"
 
 SRC_URI = "git://github.com/seccomp/libseccomp.git;branch=release-2.6;protocol=https \
+           file://0001-api-fix-seccomp_export_bpf_mem-out-of-bounds-read.patch \
            file://run-ptest \
            "