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095d141b2e
argv_split() allocates argv[count_argc(str)] array and assumes that it will find the same number of arguments later. This is obviously wrong if this string can be changed, say, by sysctl. With this patch argv_split() kstrndup's the whole string and does not split it, we simply replace the spaces with zeroes and keep the allocated memory in argv[-1] for argv_free(arg). We do not use argv[0] because: - str can be all-spaces or empty. In fact this case is fine, we could kfree() it before return, but: - str can have a space at the start, and we can not rely on kstrndup(skip_spaces(str)) because it can equally race if this string is mutable. Also, simplify count_argc() and kill the no longer used skip_arg(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
95 lines
2.1 KiB
C
95 lines
2.1 KiB
C
/*
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* Helper function for splitting a string into an argv-like array.
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*/
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#include <linux/kernel.h>
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#include <linux/ctype.h>
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#include <linux/string.h>
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#include <linux/slab.h>
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#include <linux/export.h>
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static int count_argc(const char *str)
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{
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int count = 0;
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bool was_space;
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for (was_space = true; *str; str++) {
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if (isspace(*str)) {
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was_space = true;
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} else if (was_space) {
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was_space = false;
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count++;
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}
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}
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return count;
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}
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/**
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* argv_free - free an argv
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* @argv - the argument vector to be freed
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*
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* Frees an argv and the strings it points to.
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*/
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void argv_free(char **argv)
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{
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argv--;
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kfree(argv[0]);
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kfree(argv);
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}
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EXPORT_SYMBOL(argv_free);
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/**
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* argv_split - split a string at whitespace, returning an argv
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* @gfp: the GFP mask used to allocate memory
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* @str: the string to be split
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* @argcp: returned argument count
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*
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* Returns an array of pointers to strings which are split out from
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* @str. This is performed by strictly splitting on white-space; no
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* quote processing is performed. Multiple whitespace characters are
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* considered to be a single argument separator. The returned array
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* is always NULL-terminated. Returns NULL on memory allocation
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* failure.
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*
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* The source string at `str' may be undergoing concurrent alteration via
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* userspace sysctl activity (at least). The argv_split() implementation
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* attempts to handle this gracefully by taking a local copy to work on.
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*/
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char **argv_split(gfp_t gfp, const char *str, int *argcp)
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{
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char *argv_str;
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bool was_space;
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char **argv, **argv_ret;
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int argc;
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argv_str = kstrndup(str, KMALLOC_MAX_SIZE - 1, gfp);
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if (!argv_str)
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return NULL;
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argc = count_argc(argv_str);
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argv = kmalloc(sizeof(*argv) * (argc + 2), gfp);
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if (!argv) {
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kfree(argv_str);
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return NULL;
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}
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*argv = argv_str;
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argv_ret = ++argv;
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for (was_space = true; *argv_str; argv_str++) {
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if (isspace(*argv_str)) {
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was_space = true;
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*argv_str = 0;
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} else if (was_space) {
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was_space = false;
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*argv++ = argv_str;
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}
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}
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*argv = NULL;
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if (argcp)
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*argcp = argc;
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return argv_ret;
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}
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EXPORT_SYMBOL(argv_split);
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