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kdb: Replace the use of simple_strto with safer kstrto in kdb_main

The simple_str* family of functions perform no error checking in scenarios where the input value overflows the intended output variable. This results in these functions successfully returning even when the output does not match the input string. Or as it was mentioned [1], "...simple_strtol(), simple_strtoll(), simple_strtoul(), and simple_strtoull() functions explicitly ignore overflows, which may lead to unexpected results in callers." Hence, the use of those functions is discouraged. This patch replaces all uses of the simple_strto* series of functions with their safer kstrto* alternatives. Side effects of this patch: - Every string to long or long long conversion using kstrto* is now checked for failure. - kstrto* errors are handled with appropriate `KDB_BADINT` wherever applicable. - A good side effect is that we end up saving a few lines of code since unlike in simple_strto* functions, kstrto functions do not need an additional "end pointer" variable, and the return values of the latter can be directly checked in an "if" statement without the need to define additional `ret` or `err` variables. This, of course, results in cleaner, yet still easy to understand code. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#simple-strtol-simple-strtoll-simple-strtoul-simple-strtoull

Yuran Pereira committed 2 years ago

Commit 120fb871 parent 81983751 file · +21 −48Browse files

Showing the changes to kernel/debug (1 of 1 file). Show all

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kernel/debug/kdb/kdb_main.c+21−48
@@ -306,8 +306,8 @@ static int kdbgetulenv(const char *match, unsigned long *value) · 305 unmodified lines
306306 return KDB_NOTENV;
307307 if (strlen(ep) == 0)
308308 return KDB_NOENVVALUE;
309−
310− *value = simple_strtoul(ep, NULL, 0);
309+ if (kstrtoul(ep, 0, value))
310+ return KDB_BADINT;
311311
312312 return 0;
313313 }
@@ -402,42 +402,23 @@ static void kdb_printenv(void) · 88 unmodified lines
402402 */
403403 int kdbgetularg(const char *arg, unsigned long *value)
404404 {
405− char *endp;
406− unsigned long val;
407−
408− val = simple_strtoul(arg, &endp, 0);
409−
410− if (endp == arg) {
411− /*
412− * Also try base 16, for us folks too lazy to type the
413− * leading 0x...
414− */
415− val = simple_strtoul(arg, &endp, 16);
416− if (endp == arg)
405+ /*
406+ * If the first fails, also try base 16, for us
407+ * folks too lazy to type the leading 0x...
408+ */
409+ if (kstrtoul(arg, 0, value)) {
410+ if (kstrtoul(arg, 16, value))
417411 return KDB_BADINT;
418412 }
419−
420− *value = val;
421−
422413 return 0;
423414 }
424415
425416 int kdbgetu64arg(const char *arg, u64 *value)
426417 {
427− char *endp;
428− u64 val;
429−
430− val = simple_strtoull(arg, &endp, 0);
431−
432− if (endp == arg) {
433−
434− val = simple_strtoull(arg, &endp, 16);
435− if (endp == arg)
418+ if (kstrtou64(arg, 0, value)) {
419+ if (kstrtou64(arg, 16, value))
436420 return KDB_BADINT;
437421 }
438−
439− *value = val;
440−
441422 return 0;
442423 }
443424
@@ -473,10 +454,10 @@ int kdb_set(int argc, const char **argv) · 29 unmodified lines
473454 */
474455 if (strcmp(argv[1], "KDBDEBUG") == 0) {
475456 unsigned int debugflags;
476− char *cp;
457+ int ret;
477458
478− debugflags = simple_strtoul(argv[2], &cp, 0);
479− if (cp == argv[2] || debugflags & ~KDB_DEBUG_FLAG_MASK) {
459+ ret = kstrtouint(argv[2], 0, &debugflags);
460+ if (ret || debugflags & ~KDB_DEBUG_FLAG_MASK) {
480461 kdb_printf("kdb: illegal debug flags '%s'\n",
481462 argv[2]);
482463 return 0;
@@ -1619,10 +1600,10 @@ static int kdb_md(int argc, const char **argv) · 1136 unmodified lines
16191600 if (!argv[0][3])
16201601 valid = 1;
16211602 else if (argv[0][3] == 'c' && argv[0][4]) {
1622− char *p;
1623− repeat = simple_strtoul(argv[0] + 4, &p, 10);
1603+ if (kstrtouint(argv[0] + 4, 10, &repeat))
1604+ return KDB_BADINT;
16241605 mdcount = ((repeat * bytesperword) + 15) / 16;
1625− valid = !*p;
1606+ valid = 1;
16261607 }
16271608 last_repeat = repeat;
16281609 } else if (strcmp(argv[0], "md") == 0)
@@ -2083,15 +2064,10 @@ static int kdb_dmesg(int argc, const char **argv) · 454 unmodified lines
20832064 if (argc > 2)
20842065 return KDB_ARGCOUNT;
20852066 if (argc) {
2086− char *cp;
2087− lines = simple_strtol(argv[1], &cp, 0);
2088− if (*cp)
2067+ if (kstrtoint(argv[1], 0, &lines))
20892068 lines = 0;
2090− if (argc > 1) {
2091− adjust = simple_strtoul(argv[2], &cp, 0);
2092− if (*cp || adjust < 0)
2093− adjust = 0;
2094− }
2069+ if (argc > 1 && (kstrtoint(argv[2], 0, &adjust) || adjust < 0))
2070+ adjust = 0;
20952071 }
20962072
20972073 /* disable LOGGING if set */
@@ -2428,14 +2404,12 @@ static int kdb_help(int argc, const char **argv) · 330 unmodified lines
24282404 static int kdb_kill(int argc, const char **argv)
24292405 {
24302406 long sig, pid;
2431− char *endp;
24322407 struct task_struct *p;
24332408
24342409 if (argc != 2)
24352410 return KDB_ARGCOUNT;
24362411
2437− sig = simple_strtol(argv[1], &endp, 0);
2438− if (*endp)
2412+ if (kstrtol(argv[1], 0, &sig))
24392413 return KDB_BADINT;
24402414 if ((sig >= 0) || !valid_signal(-sig)) {
24412415 kdb_printf("Invalid signal parameter.<-signal>\n");
@@ -2443,8 +2417,7 @@ static int kdb_kill(int argc, const char **argv) · 1 unmodified line
24432417 }
24442418 sig = -sig;
24452419
2446− pid = simple_strtol(argv[2], &endp, 0);
2447− if (*endp)
2420+ if (kstrtol(argv[2], 0, &pid))
24482421 return KDB_BADINT;
24492422 if (pid <= 0) {
24502423 kdb_printf("Process ID must be large than 0.\n");