diff --git a/kernel/module.c b/kernel/module.c
index e7b4ff7e4fd07ffaac032c06a28ccd082e431213..8fa2600bde6a39a62ba08c08cecbf2b054409635 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1520,18 +1520,34 @@ struct module_sect_attrs {
struct module_sect_attr attrs[];
};
+#define MODULE_SECT_READ_SIZE (3 /* "0x", "\n" */ + (BITS_PER_LONG / 4))
static ssize_t module_sect_read(struct file *file, struct kobject *kobj,
struct bin_attribute *battr,
char *buf, loff_t pos, size_t count)
{
struct module_sect_attr *sattr =
container_of(battr, struct module_sect_attr, battr);
+ char bounce[MODULE_SECT_READ_SIZE + 1];
+ size_t wrote;
if (pos != 0)
return -EINVAL;
- return sprintf(buf, "0x%px\n",
- kallsyms_show_value(file->f_cred) ? (void *)sattr->address : NULL);
+ /*
+ * Since we're a binary read handler, we must account for the
+ * trailing NUL byte that sprintf will write: if "buf" is
+ * too small to hold the NUL, or the NUL is exactly the last
+ * byte, the read will look like it got truncated by one byte.
+ * Since there is no way to ask sprintf nicely to not write
+ * the NUL, we have to use a bounce buffer.
+ */
+ wrote = scnprintf(bounce, sizeof(bounce), "0x%px\n",
+ kallsyms_show_value(file->f_cred)
+ ? (void *)sattr->address : NULL);
+ count = min(count, wrote);
+ memcpy(buf, bounce, count);
+
+ return count;
}
static void free_sect_attrs(struct module_sect_attrs *sect_attrs)
@@ -1580,7 +1596,7 @@ static void add_sect_attrs(struct module *mod, const struct load_info *info)
goto out;
sect_attrs->nsections++;
sattr->battr.read = module_sect_read;
- sattr->battr.size = 3 /* "0x", "\n" */ + (BITS_PER_LONG / 4);
+ sattr->battr.size = MODULE_SECT_READ_SIZE;
sattr->battr.attr.mode = 0400;
*(gattr++) = &(sattr++)->battr;
}
diff --git a/tools/testing/selftests/splice/.gitignore b/tools/testing/selftests/splice/.gitignore
index d5a2da428752a4b4c81e4b6354efc842b8e2899a..be8266f5d04c03f1a2d9c04d1f35338cd3c38ee7 100644
--- a/tools/testing/selftests/splice/.gitignore
+++ b/tools/testing/selftests/splice/.gitignore
@@ -1,2 +1,3 @@
# SPDX-License-Identifier: GPL-2.0-only
default_file_splice_read
+splice_read
diff --git a/tools/testing/selftests/splice/Makefile b/tools/testing/selftests/splice/Makefile
index e519b159b60d83fdc14d8ab263387906d6cf1228..541cd826d5a55eee5642c1940b6bf1d1e0a938e9 100644
--- a/tools/testing/selftests/splice/Makefile
+++ b/tools/testing/selftests/splice/Makefile
@@ -1,5 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
-TEST_PROGS := default_file_splice_read.sh
-TEST_GEN_PROGS_EXTENDED := default_file_splice_read
+TEST_PROGS := default_file_splice_read.sh short_splice_read.sh
+TEST_GEN_PROGS_EXTENDED := default_file_splice_read splice_read
include ../lib.mk
diff --git a/tools/testing/selftests/splice/config b/tools/testing/selftests/splice/config
new file mode 100644
index 0000000000000000000000000000000000000000..058c928368b8923f151719134b07a006e49e6f0f
--- /dev/null
+++ b/tools/testing/selftests/splice/config
@@ -0,0 +1 @@
+CONFIG_TEST_LKM=m
diff --git a/tools/testing/selftests/splice/settings b/tools/testing/selftests/splice/settings
new file mode 100644
index 0000000000000000000000000000000000000000..89cedfc0d12b1f739bb8cac7172956c23106031d
--- /dev/null
+++ b/tools/testing/selftests/splice/settings
@@ -0,0 +1 @@
+timeout=5
diff --git a/tools/testing/selftests/splice/short_splice_read.sh b/tools/testing/selftests/splice/short_splice_read.sh
new file mode 100755
index 0000000000000000000000000000000000000000..7810d3589d9ab0ef5a491cca24d0f09c4177b369
--- /dev/null
+++ b/tools/testing/selftests/splice/short_splice_read.sh
@@ -0,0 +1,56 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+set -e
+
+ret=0
+
+do_splice()
+{
+ filename="$1"
+ bytes="$2"
+ expected="$3"
+
+ out=$(./splice_read "$filename" "$bytes" | cat)
+ if [ "$out" = "$expected" ] ; then
+ echo "ok: $filename $bytes"
+ else
+ echo "FAIL: $filename $bytes"
+ ret=1
+ fi
+}
+
+test_splice()
+{
+ filename="$1"
+
+ full=$(cat "$filename")
+ two=$(echo "$full" | grep -m1 . | cut -c-2)
+
+ # Make sure full splice has the same contents as a standard read.
+ do_splice "$filename" 4096 "$full"
+
+ # Make sure a partial splice see the first two characters.
+ do_splice "$filename" 2 "$two"
+}
+
+# proc_single_open(), seq_read()
+test_splice /proc/$$/limits
+# special open, seq_read()
+test_splice /proc/$$/comm
+
+# proc_handler, proc_dointvec_minmax
+test_splice /proc/sys/fs/nr_open
+# proc_handler, proc_dostring
+test_splice /proc/sys/kernel/modprobe
+# proc_handler, special read
+test_splice /proc/sys/kernel/version
+
+if ! [ -d /sys/module/test_module/sections ] ; then
+ modprobe test_module
+fi
+# kernfs, attr
+test_splice /sys/module/test_module/coresize
+# kernfs, binattr
+test_splice /sys/module/test_module/sections/.init.text
+
+exit $ret
diff --git a/tools/testing/selftests/splice/splice_read.c b/tools/testing/selftests/splice/splice_read.c
new file mode 100644
index 0000000000000000000000000000000000000000..46dae6a25cfb9562970421eb05d4adf5461e6767
--- /dev/null
+++ b/tools/testing/selftests/splice/splice_read.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+int main(int argc, char *argv[])
+{
+ int fd;
+ size_t size;
+ ssize_t spliced;
+
+ if (argc < 2) {
+ fprintf(stderr, "Usage: %s INPUT [BYTES]\n", argv[0]);
+ return EXIT_FAILURE;
+ }
+
+ fd = open(argv[1], O_RDONLY);
+ if (fd < 0) {
+ perror(argv[1]);
+ return EXIT_FAILURE;
+ }
+
+ if (argc == 3)
+ size = atol(argv[2]);
+ else {
+ struct stat statbuf;
+
+ if (fstat(fd, &statbuf) < 0) {
+ perror(argv[1]);
+ return EXIT_FAILURE;
+ }
+
+ if (statbuf.st_size > INT_MAX) {
+ fprintf(stderr, "%s: Too big\n", argv[1]);
+ return EXIT_FAILURE;
+ }
+
+ size = statbuf.st_size;
+ }
+
+ /* splice(2) file to stdout. */
+ spliced = splice(fd, NULL, STDOUT_FILENO, NULL,
+ size, SPLICE_F_MOVE);
+ if (spliced < 0) {
+ perror("splice");
+ return EXIT_FAILURE;
+ }
+
+ close(fd);
+ return EXIT_SUCCESS;
+}