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Rasmus Villemoes
8e2a2bfdb8
kasprintf relies on being able to replay the formatting and getting the same result (in particular, the same length). This will almost always work, but it is possible that the object pointed to by a %s or %p argument changed under us (so we might get truncated output). Add a somewhat paranoid sanity check and let's see if it ever triggers. Signed-off-by: Rasmus Villemoes <[email protected]> Cc: Al Viro <[email protected]> Cc: Andy Shevchenko <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Joe Perches <[email protected]> Cc: Kees Cook <[email protected]> Cc: Maurizio Lombardi <[email protected]> Cc: Tejun Heo <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
64 lines
1.4 KiB
C
64 lines
1.4 KiB
C
/*
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* linux/lib/kasprintf.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <stdarg.h>
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#include <linux/export.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/string.h>
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/* Simplified asprintf. */
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char *kvasprintf(gfp_t gfp, const char *fmt, va_list ap)
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{
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unsigned int first, second;
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char *p;
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va_list aq;
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va_copy(aq, ap);
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first = vsnprintf(NULL, 0, fmt, aq);
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va_end(aq);
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p = kmalloc_track_caller(first+1, gfp);
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if (!p)
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return NULL;
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second = vsnprintf(p, first+1, fmt, ap);
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WARN(first != second, "different return values (%u and %u) from vsnprintf(\"%s\", ...)",
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first, second, fmt);
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return p;
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}
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EXPORT_SYMBOL(kvasprintf);
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/*
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* If fmt contains no % (or is exactly %s), use kstrdup_const. If fmt
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* (or the sole vararg) points to rodata, we will then save a memory
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* allocation and string copy. In any case, the return value should be
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* freed using kfree_const().
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*/
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const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list ap)
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{
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if (!strchr(fmt, '%'))
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return kstrdup_const(fmt, gfp);
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if (!strcmp(fmt, "%s"))
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return kstrdup_const(va_arg(ap, const char*), gfp);
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return kvasprintf(gfp, fmt, ap);
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}
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EXPORT_SYMBOL(kvasprintf_const);
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char *kasprintf(gfp_t gfp, const char *fmt, ...)
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{
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va_list ap;
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char *p;
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va_start(ap, fmt);
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p = kvasprintf(gfp, fmt, ap);
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va_end(ap);
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return p;
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}
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EXPORT_SYMBOL(kasprintf);
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