Avoid use of atoi in some places in libc

This patch is split out of
<https://sourceware.org/pipermail/libc-alpha/2022-December/144122.html>.

atoi has undefined behavior on out-of-range input, which makes it
problematic to use anywhere in glibc that might be processing input
out-of-range for atoi but not specified to produce undefined behavior
for the function calling atoi.  Change some uses of atoi to call
strtol instead; this avoids the undefined behavior, though there is no
guarantee that the overflow handling of strtol is really right in
those places either.  This also serves to avoid localplt test failures
given an installed header redirection for strtol (which means that the
call from the inline atoi implementation doesn't end up at a hidden
alias from libc_hidden_proto).

Certainly, the use of atoi is questionable in argp-help.c (shared with
gnulib, so shouldn't depend on glibc implementation details, and
processing user-provided input), and maybe also in argp-parse.c (I'm
not sure what that code in argp-parse.c is meant to be used for).  I
also changed inet/rexec.c and resolv/res_init.c similarly to use
strtol to avoid such localplt failures, although given those files (in
those versions) are only used in glibc it's not problematic for them
to rely on the specific behavior of glibc's atoi on out-of-range input
(in the absence of compiler optimizations based on the undefined
behavior) in the same way it's problematic for gnulib code to do so.

There may be other uses of atoi (or atol or atoll), in any of glibc's
installed code, for which it would also be appropriate to avoid the
undefined behavior on out-of-range input; this patch only fixes the
specific cases needed to avoid localplt failures.

Tested for x86_64.

diff --git a/argp/argp-help.c b/argp/argp-help.c
index 90a2795cefd2bdaf5a6c3efcb0ada20531b0611f..f7f1134c80193a719908d7ecaa317f4e093d1492 100644 (file)
--- a/argp/argp-help.c
+++ b/argp/argp-help.c
@@ -210,9 +210,9 @@ fill_in_uparams (const struct argp_state *state)
              }
            else if (isdigit ((unsigned char) *arg))
              {
-               val = atoi (arg);
-               while (isdigit ((unsigned char) *arg))
-                 arg++;
+               char *ep;
+               val = strtol (arg, &ep, 10);
+               arg = ep;
                SKIPWS (arg);
              }
 

diff --git a/argp/argp-parse.c b/argp/argp-parse.c
index 68dc45417b86a0ffd422a388db081b8ca72a5c9e..1533b43aaf1d569ae6daf77dc0a73a07d073c38e 100644 (file)
--- a/argp/argp-parse.c
+++ b/argp/argp-parse.c
@@ -147,7 +147,7 @@ argp_default_parser (int key, char *arg, struct argp_state *state)
       break;
 
     case OPT_HANG:
-      _argp_hang = atoi (arg ? arg : "3600");
+      _argp_hang = arg ? strtol (arg, NULL, 10) : 3600;
       while (_argp_hang-- > 0)
        __sleep (1);
       break;

diff --git a/inet/rexec.c b/inet/rexec.c
index 064e979d68b64c8f17be3754b8cc1f520bc30a38..c647b7ac34e6184bbee7d045b491126f5f85832d 100644 (file)
--- a/inet/rexec.c
+++ b/inet/rexec.c
@@ -134,7 +134,7 @@ retry:
                if (!getnameinfo(&sa2.sa, sa2len,
                                 NULL, 0, servbuff, sizeof(servbuff),
                                 NI_NUMERICSERV))
-                       port = atoi(servbuff);
+                       port = strtol(servbuff, NULL, 10);
                (void) sprintf(num, "%u", port);
                (void) __write(s, num, strlen(num)+1);
                { socklen_t len = sizeof (from);

diff --git a/resolv/res_init.c b/resolv/res_init.c
index 2c0bea658e774ae769c9096f2226c88ceef10671..61b958a437f5463064bdff576c4df3bfc866fcbd 100644 (file)
--- a/resolv/res_init.c
+++ b/resolv/res_init.c
@@ -654,7 +654,7 @@ res_setoptions (struct resolv_conf_parser *parser, const char *options)
       /* Search for and process individual options.  */
       if (!strncmp (cp, "ndots:", sizeof ("ndots:") - 1))
         {
-          int i = atoi (cp + sizeof ("ndots:") - 1);
+          int i = strtol (cp + sizeof ("ndots:") - 1, NULL, 10);
           if (i <= RES_MAXNDOTS)
             parser->template.ndots = i;
           else
@@ -662,7 +662,7 @@ res_setoptions (struct resolv_conf_parser *parser, const char *options)
         }
       else if (!strncmp (cp, "timeout:", sizeof ("timeout:") - 1))
         {
-          int i = atoi (cp + sizeof ("timeout:") - 1);
+          int i = strtol (cp + sizeof ("timeout:") - 1, NULL, 10);
           if (i <= RES_MAXRETRANS)
             parser->template.retrans = i;
           else
@@ -670,7 +670,7 @@ res_setoptions (struct resolv_conf_parser *parser, const char *options)
         }
       else if (!strncmp (cp, "attempts:", sizeof ("attempts:") - 1))
         {
-          int i = atoi (cp + sizeof ("attempts:") - 1);
+          int i = strtol (cp + sizeof ("attempts:") - 1, NULL, 10);
           if (i <= RES_MAXRETRY)
             parser->template.retry = i;
           else