mem-pool: use st_add() in mem_pool_strvfmt()
If len is INT_MAX in mem_pool_strvfmt(), then len + 1 overflows. Casting it to size_t would prevent that. Use st_add() to go a step further and make the addition *obviously* safe. The compiler can optimize the check away on platforms where SIZE_MAX > INT_MAX, i.e. basically everywhere. Signed-off-by: René Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
René Scharfe committed
Mar 31, 2024 at 20:53 UTC
ffeaf2f76ab422428d6190d0cfbca2f34f06602a
1 file changed
+4
-2
mem-pool.c
+4
-2
@@ -115,6 +115,7 @@ static char *mem_pool_strvfmt(struct mem_pool *pool, const char *fmt,
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size_t available = block ? block->end - block->next_free : 0;
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va_list cp;
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int len, len2;
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+ size_t size;
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char *ret;
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va_copy(cp, ap);
@@ -123,13 +124,14 @@ static char *mem_pool_strvfmt(struct mem_pool *pool, const char *fmt,
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if (len < 0)
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BUG("your vsnprintf is broken (returned %d)", len);
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- ret = mem_pool_alloc(pool, len + 1); /* 1 for NUL */
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+ size = st_add(len, 1); /* 1 for NUL */
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+ ret = mem_pool_alloc(pool, size);
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/* Shortcut; relies on mem_pool_alloc() not touching buffer contents. */
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if (ret == next_free)
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return ret;
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- len2 = vsnprintf(ret, len + 1, fmt, ap);
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+ len2 = vsnprintf(ret, size, fmt, ap);
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if (len2 != len)
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BUG("your vsnprintf is broken (returns inconsistent lengths)");
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return ret;