treewide: Comply with CERT C rule ERR33-C for snprintf()
clang-tidy, starting from LLVM version 16, up to at least LLVM version
19, now checks that we detect and handle errors for snprintf() as
requested by CERT C rule ERR33-C. These warnings were logged with LLVM
version 19.1.2 (at least Debian and Fedora match):
/home/sbrivio/passt/arch.c:43:3: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
43 | snprintf(new_path, PATH_MAX + sizeof(".avx2"), "%s.avx2", exe);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sbrivio/passt/arch.c:43:3: note: cast the expression to void to silence this warning
/home/sbrivio/passt/conf.c:577:4: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
577 | snprintf(netns, PATH_MAX, "/proc/%ld/ns/net", pidval);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sbrivio/passt/conf.c:577:4: note: cast the expression to void to silence this warning
/home/sbrivio/passt/conf.c:579:5: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
579 | snprintf(userns, PATH_MAX, "/proc/%ld/ns/user",
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
580 | pidval);
| ~~~~~~~
/home/sbrivio/passt/conf.c:579:5: note: cast the expression to void to silence this warning
/home/sbrivio/passt/pasta.c:105:2: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
105 | snprintf(ns, PATH_MAX, "/proc/%i/ns/net", pasta_child_pid);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sbrivio/passt/pasta.c:105:2: note: cast the expression to void to silence this warning
/home/sbrivio/passt/pasta.c:242:2: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
242 | snprintf(uidmap, BUFSIZ, "0 %u 1", uid);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sbrivio/passt/pasta.c:242:2: note: cast the expression to void to silence this warning
/home/sbrivio/passt/pasta.c:243:2: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
243 | snprintf(gidmap, BUFSIZ, "0 %u 1", gid);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sbrivio/passt/pasta.c:243:2: note: cast the expression to void to silence this warning
/home/sbrivio/passt/tap.c:1155:4: error: the value returned by this function should not be disregarded; neglecting it may lead to errors [cert-err33-c,-warnings-as-errors]
1155 | snprintf(path, UNIX_PATH_MAX - 1, UNIX_SOCK_PATH, i);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sbrivio/passt/tap.c:1155:4: note: cast the expression to void to silence this warning
Don't silence the warnings as they might actually have some merit. Add
an snprintf_check() function, instead, checking that we're not
truncating messages while printing to buffers, and terminate if the
check fails.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Stefano Brivio
parent
988a4d75f8
commit
98efe7c2fd
6 changed files with 57 additions and 10 deletions
6
arch.c
6
arch.c
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@ -19,6 +19,7 @@
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#include <unistd.h>
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#include "log.h"
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#include "util.h"
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/**
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* arch_avx2_exec() - Switch to AVX2 build if supported
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@ -40,7 +41,10 @@ void arch_avx2_exec(char **argv)
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if (__builtin_cpu_supports("avx2")) {
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char new_path[PATH_MAX + sizeof(".avx2")];
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snprintf(new_path, PATH_MAX + sizeof(".avx2"), "%s.avx2", exe);
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if (snprintf_check(new_path, PATH_MAX + sizeof(".avx2"),
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"%s.avx2", exe))
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die_perror("Can't build AVX2 executable path");
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execve(new_path, argv, environ);
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warn_perror("Can't run AVX2 build, using non-AVX2 version");
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}
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13
conf.c
13
conf.c
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@ -574,10 +574,15 @@ static void conf_pasta_ns(int *netns_only, char *userns, char *netns,
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if (pidval < 0 || pidval > INT_MAX)
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die("Invalid PID %s", argv[optind]);
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snprintf(netns, PATH_MAX, "/proc/%ld/ns/net", pidval);
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if (!*userns)
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snprintf(userns, PATH_MAX, "/proc/%ld/ns/user",
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pidval);
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if (snprintf_check(netns, PATH_MAX,
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"/proc/%ld/ns/net", pidval))
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die_perror("Can't build netns path");
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if (!*userns) {
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if (snprintf_check(userns, PATH_MAX,
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"/proc/%ld/ns/user", pidval))
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die_perror("Can't build userns path");
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}
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}
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}
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11
pasta.c
11
pasta.c
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@ -102,7 +102,9 @@ static int pasta_wait_for_ns(void *arg)
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int flags = O_RDONLY | O_CLOEXEC;
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char ns[PATH_MAX];
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snprintf(ns, PATH_MAX, "/proc/%i/ns/net", pasta_child_pid);
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if (snprintf_check(ns, PATH_MAX, "/proc/%i/ns/net", pasta_child_pid))
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die_perror("Can't build netns path");
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do {
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while ((c->pasta_netns_fd = open(ns, flags)) < 0) {
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if (errno != ENOENT)
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@ -239,8 +241,11 @@ void pasta_start_ns(struct ctx *c, uid_t uid, gid_t gid,
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c->quiet = 1;
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/* Configure user and group mappings */
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snprintf(uidmap, BUFSIZ, "0 %u 1", uid);
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snprintf(gidmap, BUFSIZ, "0 %u 1", gid);
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if (snprintf_check(uidmap, BUFSIZ, "0 %u 1", uid))
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die_perror("Can't build uidmap");
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if (snprintf_check(gidmap, BUFSIZ, "0 %u 1", gid))
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die_perror("Can't build gidmap");
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if (write_file("/proc/self/uid_map", uidmap) ||
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write_file("/proc/self/setgroups", "deny") ||
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5
tap.c
5
tap.c
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@ -1151,8 +1151,9 @@ int tap_sock_unix_open(char *sock_path)
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if (*sock_path)
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memcpy(path, sock_path, UNIX_PATH_MAX);
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else
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snprintf(path, UNIX_PATH_MAX - 1, UNIX_SOCK_PATH, i);
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else if (snprintf_check(path, UNIX_PATH_MAX - 1,
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UNIX_SOCK_PATH, i))
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die_perror("Can't build UNIX domain socket path");
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ex = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0);
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if (ex < 0)
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30
util.c
30
util.c
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@ -749,3 +749,33 @@ void close_open_files(int argc, char **argv)
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if (rc)
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die_perror("Failed to close files leaked by parent");
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}
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/**
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* snprintf_check() - snprintf() wrapper, checking for truncation and errors
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* @str: Output buffer
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* @size: Maximum size to write to @str
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* @format: Message
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*
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* Return: false on success, true on truncation or error, sets errno on failure
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*/
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bool snprintf_check(char *str, size_t size, const char *format, ...)
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{
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va_list ap;
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int rc;
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va_start(ap, format);
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rc = vsnprintf(str, size, format, ap);
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va_end(ap);
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if (rc < 0) {
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errno = EIO;
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return true;
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}
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if ((size_t)rc >= size) {
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errno = ENOBUFS;
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return true;
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}
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return false;
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}
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2
util.h
2
util.h
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@ -11,6 +11,7 @@
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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#include <signal.h>
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#include <arpa/inet.h>
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@ -200,6 +201,7 @@ int write_file(const char *path, const char *buf);
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int write_all_buf(int fd, const void *buf, size_t len);
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int write_remainder(int fd, const struct iovec *iov, size_t iovcnt, size_t skip);
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void close_open_files(int argc, char **argv);
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bool snprintf_check(char *str, size_t size, const char *format, ...);
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/**
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* af_name() - Return name of an address family
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