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Fix potential UB issues #437

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Fix potential UB issues #437

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47 changes: 32 additions & 15 deletions src/exec_ptrace.c
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Original file line number Diff line number Diff line change
Expand Up @@ -415,9 +415,12 @@ ptrace_readv_string(pid_t pid, unsigned long addr, char *buf, size_t bufsize)
static ssize_t
ptrace_read_string(pid_t pid, unsigned long addr, char *buf, size_t bufsize)
{
const char *cp, *buf0 = buf;
unsigned long word;
const char *buf0 = buf;
size_t i;
union {
unsigned long word;
char buf[sizeof(unsigned long)];
} u;
debug_decl(ptrace_read_string, SUDO_DEBUG_EXEC);

#ifdef HAVE_PROCESS_VM_READV
Expand All @@ -432,28 +435,27 @@ ptrace_read_string(pid_t pid, unsigned long addr, char *buf, size_t bufsize)
* is the unit ptrace(2) uses.
*/
for (;;) {
word = ptrace(PTRACE_PEEKDATA, pid, addr, NULL);
if (word == (unsigned long)-1) {
u.word = ptrace(PTRACE_PEEKDATA, pid, addr, NULL);
if (u.word == (unsigned long)-1) {
sudo_debug_printf(
SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO|SUDO_DEBUG_ERRNO,
"ptrace(PTRACE_PEEKDATA, %d, 0x%lx, NULL)", (int)pid, addr);
debug_return_ssize_t(-1);
}

cp = (char *)&word;
for (i = 0; i < sizeof(unsigned long); i++) {
for (i = 0; i < sizeof(u.buf); i++) {
if (bufsize == 0) {
sudo_debug_printf(SUDO_DEBUG_ERROR,
"%s: %d: out of space reading string", __func__, (int)pid);
errno = ENOSPC;
debug_return_ssize_t(-1);
}
*buf = cp[i];
*buf = u.buf[i];
if (*buf++ == '\0')
debug_return_ssize_t(buf - buf0);
bufsize--;
}
addr += sizeof(unsigned long);
addr += sizeof(u.word);
}
}

Expand All @@ -469,6 +471,12 @@ growbuf(char **bufp, size_t *bufsizep, char **curp, size_t *remp)
char *newbuf;
debug_decl(growbuf, SUDO_DEBUG_EXEC);

/* Check for overflow when doubling the size of the buffer. */
if (oldsize > SIZE_MAX / 2) {
sudo_warnx(U_("%s: %s"), __func__, U_("buffer size overflow"));
debug_return_bool(false);
}

/* Double the size of the buffer. */
newbuf = reallocarray(*bufp, 2, oldsize);
if (newbuf == NULL) {
Expand Down Expand Up @@ -952,14 +960,23 @@ proc_read_link(pid_t pid, const char *name, char *buf, size_t bufsize)
char path[PATH_MAX];
debug_decl(proc_read_link, SUDO_DEBUG_EXEC);

/* Ensure minimum buffer size and termination */
if (bufsize < 2) {
errno = EOVERFLOW;
debug_return_bool(false);
}

len = snprintf(path, sizeof(path), "/proc/%d/%s", (int)pid, name);
if (len > 0 && len < ssizeof(path)) {
len = readlink(path, buf, bufsize - 1);
if (len != -1) {
/* readlink(2) does not add the NUL for us. */
buf[len] = '\0';
debug_return_bool(true);
}
if (len < 0 || len >= ssizeof(path)) {
errno = ENAMETOOLONG;
debug_return_bool(false);
}

len = readlink(path, buf, bufsize - 1);
if (len != -1) {
/* readlink(2) does not add the NUL for us. */
buf[len] = '\0';
debug_return_bool(true);
}
debug_return_bool(false);
}
Expand Down