| Message ID | GV1PR10MB6563E0F8DB2D335BD9CFE4D3E8B4A@GV1PR10MB6563.EURPRD10.PROD.OUTLOOK.COM (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | Replace the use of simple_strtol/ul functions with kstrto | expand |
Hi, On Sun, Nov 19, 2023 at 4:07 PM Yuran Pereira <yuran.pereira@hotmail.com> wrote: > > 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 > > Signed-off-by: Yuran Pereira <yuran.pereira@hotmail.com> > --- > kernel/debug/kdb/kdb_main.c | 70 +++++++++++-------------------------- > 1 file changed, 21 insertions(+), 49 deletions(-) Sorry for taking so long to review this--it arrived in my inbox at a bad time. A few minor nits below that I think should be fixed before landing but overall I think it's a nice cleanup. Thanks! > @@ -412,42 +412,21 @@ static void kdb_printenv(void) > */ > int kdbgetularg(const char *arg, unsigned long *value) > { > - char *endp; > - unsigned long val; > - > - val = simple_strtoul(arg, &endp, 0); > - > - if (endp == arg) { > - /* > - * Also try base 16, for us folks too lazy to type the > - * leading 0x... > - */ > - val = simple_strtoul(arg, &endp, 16); > - if (endp == arg) > + /* > + * If the first fails, also try base 16, for us > + * folks too lazy to type the leading 0x... > + */ > + if (kstrtoul(arg, 0, value)) > + if (kstrtoul(arg, 16, value)) Not new to your patch, but the above seems like a terrible idea to me. What that means is that: kdbgetularg("18", &value) => value is 18 kdbgetularg("19", &value) => value is 19 kdbgetularg("1a", &value) => value is 26 Bleh! If someone wants hex then they should put the 0x first. I'd suggest a followup patch that removes the fallback for the lazy folks. Here and in the next function... > @@ -2095,15 +2074,11 @@ static int kdb_dmesg(int argc, const char **argv) > if (argc > 2) > return KDB_ARGCOUNT; > if (argc) { > - char *cp; > - lines = simple_strtol(argv[1], &cp, 0); > - if (*cp) > + if (kstrtoint(argv[1], 0, &lines)) > lines = 0; > - if (argc > 1) { > - adjust = simple_strtoul(argv[2], &cp, 0); > - if (*cp || adjust < 0) > + if (argc > 1) > + if (kstrtouint(argv[2], 0, &adjust) || adjust < 0) My gut reaction is that some sort of build bot is going to come and yell at you about the above line. Even if it doesn't, it's a bit confusing. You're passing a pointer to an int into a function that expects a pointer to an unsigned int. Most things don't really care about signed/unsigned, but I could swear that some compilers get mad when you start working with pointers to those types... In any case, I think everything would work fine if you just change it to kstrtoint(), right? I guess the other option would be to change the variable to unsigned, but I guess that doesn't make sense since it's a modifier to "lines" which is an int. Side note: I didn't even know about the "adjust" argument, since it's not in the help text in the command table below. I guess that could be fixed in a separate patch. nit: IMO if you have nested "if" statements then the outer one should have braces. AKA: if (a) { if (b) blah(); } instead of: if (a) if (b) blah(); ...or you could do better and just change it to: if (a && b) blah();
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index 6b213c8252d6..a6e4bec7854d 100644 --- a/kernel/debug/kdb/kdb_main.c +++ b/kernel/debug/kdb/kdb_main.c @@ -316,8 +316,8 @@ static int kdbgetulenv(const char *match, unsigned long *value) return KDB_NOTENV; if (strlen(ep) == 0) return KDB_NOENVVALUE; - - *value = simple_strtoul(ep, NULL, 0); + if (kstrtoul(ep, 0, value)) + return KDB_BADINT; return 0; } @@ -412,42 +412,21 @@ static void kdb_printenv(void) */ int kdbgetularg(const char *arg, unsigned long *value) { - char *endp; - unsigned long val; - - val = simple_strtoul(arg, &endp, 0); - - if (endp == arg) { - /* - * Also try base 16, for us folks too lazy to type the - * leading 0x... - */ - val = simple_strtoul(arg, &endp, 16); - if (endp == arg) + /* + * If the first fails, also try base 16, for us + * folks too lazy to type the leading 0x... + */ + if (kstrtoul(arg, 0, value)) + if (kstrtoul(arg, 16, value)) return KDB_BADINT; - } - - *value = val; - return 0; } int kdbgetu64arg(const char *arg, u64 *value) { - char *endp; - u64 val; - - val = simple_strtoull(arg, &endp, 0); - - if (endp == arg) { - - val = simple_strtoull(arg, &endp, 16); - if (endp == arg) + if (kstrtou64(arg, 0, value)) + if (kstrtou64(arg, 16, value)) return KDB_BADINT; - } - - *value = val; - return 0; } @@ -483,10 +462,10 @@ int kdb_set(int argc, const char **argv) */ if (strcmp(argv[1], "KDBDEBUG") == 0) { unsigned int debugflags; - char *cp; + int ret; - debugflags = simple_strtoul(argv[2], &cp, 0); - if (cp == argv[2] || debugflags & ~KDB_DEBUG_FLAG_MASK) { + ret = kstrtouint(argv[2], 0, &debugflags); + if (ret || debugflags & ~KDB_DEBUG_FLAG_MASK) { kdb_printf("kdb: illegal debug flags '%s'\n", argv[2]); return 0; @@ -1631,10 +1610,10 @@ static int kdb_md(int argc, const char **argv) if (!argv[0][3]) valid = 1; else if (argv[0][3] == 'c' && argv[0][4]) { - char *p; - repeat = simple_strtoul(argv[0] + 4, &p, 10); + if (kstrtouint(argv[0] + 4, 10, &repeat)) + return KDB_BADINT; mdcount = ((repeat * bytesperword) + 15) / 16; - valid = !*p; + valid = 1; } last_repeat = repeat; } else if (strcmp(argv[0], "md") == 0) @@ -2095,15 +2074,11 @@ static int kdb_dmesg(int argc, const char **argv) if (argc > 2) return KDB_ARGCOUNT; if (argc) { - char *cp; - lines = simple_strtol(argv[1], &cp, 0); - if (*cp) + if (kstrtoint(argv[1], 0, &lines)) lines = 0; - if (argc > 1) { - adjust = simple_strtoul(argv[2], &cp, 0); - if (*cp || adjust < 0) + if (argc > 1) + if (kstrtouint(argv[2], 0, &adjust) || adjust < 0) adjust = 0; - } } /* disable LOGGING if set */ @@ -2440,14 +2415,12 @@ static int kdb_help(int argc, const char **argv) static int kdb_kill(int argc, const char **argv) { long sig, pid; - char *endp; struct task_struct *p; if (argc != 2) return KDB_ARGCOUNT; - sig = simple_strtol(argv[1], &endp, 0); - if (*endp) + if (kstrtol(argv[1], 0, &sig)) return KDB_BADINT; if ((sig >= 0) || !valid_signal(-sig)) { kdb_printf("Invalid signal parameter.<-signal>\n"); @@ -2455,8 +2428,7 @@ static int kdb_kill(int argc, const char **argv) } sig = -sig; - pid = simple_strtol(argv[2], &endp, 0); - if (*endp) + if (kstrtol(argv[2], 0, &pid)) return KDB_BADINT; if (pid <= 0) { kdb_printf("Process ID must be large than 0.\n");
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 Signed-off-by: Yuran Pereira <yuran.pereira@hotmail.com> --- kernel/debug/kdb/kdb_main.c | 70 +++++++++++-------------------------- 1 file changed, 21 insertions(+), 49 deletions(-)