forked from pool/busybox
81 lines
2.7 KiB
Diff
81 lines
2.7 KiB
Diff
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From d417193cf37ca1005830d7e16f5fa7e1d8a44209 Mon Sep 17 00:00:00 2001
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From: Denys Vlasenko <vda.linux@googlemail.com>
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Date: Mon, 12 Jun 2023 17:48:47 +0200
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Subject: [PATCH] shell: avoid segfault on ${0::0/0~09J}. Closes 15216
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function old new delta
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evaluate_string 1011 1053 +42
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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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---
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shell/math.c | 39 +++++++++++++++++++++++++++++++++++----
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1 file changed, 35 insertions(+), 4 deletions(-)
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diff --git a/shell/math.c b/shell/math.c
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index 76d22c9bd..727c29467 100644
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--- a/shell/math.c
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+++ b/shell/math.c
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@@ -577,6 +577,28 @@ static arith_t strto_arith_t(const char *nptr, char **endptr)
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# endif
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#endif
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+//TODO: much better estimation than expr_len/2? Such as:
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+//static unsigned estimate_nums_and_names(const char *expr)
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+//{
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+// unsigned count = 0;
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+// while (*(expr = skip_whitespace(expr)) != '\0') {
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+// const char *p;
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+// if (isdigit(*expr)) {
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+// while (isdigit(*++expr))
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+// continue;
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+// count++;
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+// continue;
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+// }
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+// p = endofname(expr);
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+// if (p != expr) {
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+// expr = p;
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+// count++;
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+// continue;
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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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static arith_t
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evaluate_string(arith_state_t *math_state, const char *expr)
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{
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@@ -584,10 +606,12 @@ evaluate_string(arith_state_t *math_state, const char *expr)
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const char *errmsg;
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const char *start_expr = expr = skip_whitespace(expr);
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unsigned expr_len = strlen(expr) + 2;
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- /* Stack of integers */
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- /* The proof that there can be no more than strlen(startbuf)/2+1
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- * integers in any given correct or incorrect expression
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- * is left as an exercise to the reader. */
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+ /* Stack of integers/names */
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+ /* There can be no more than strlen(startbuf)/2+1
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+ * integers/names in any given correct or incorrect expression.
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+ * (modulo "09v09v09v09v09v" case,
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+ * but we have code to detect that early)
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+ */
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var_or_num_t *const numstack = alloca((expr_len / 2) * sizeof(numstack[0]));
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var_or_num_t *numstackptr = numstack;
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/* Stack of operator tokens */
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@@ -652,6 +676,13 @@ evaluate_string(arith_state_t *math_state, const char *expr)
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numstackptr->var = NULL;
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errno = 0;
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numstackptr->val = strto_arith_t(expr, (char**) &expr);
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+ /* A number can't be followed by another number, or a variable name.
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+ * We'd catch this later anyway, but this would require numstack[]
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+ * to be twice as deep to handle strings where _every_ char is
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+ * a new number or name. Example: 09v09v09v09v09v09v09v09v09v
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+ */
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+ if (isalnum(*expr) || *expr == '_')
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+ goto err;
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//bb_error_msg("val:%lld", numstackptr->val);
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if (errno)
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numstackptr->val = 0; /* bash compat */
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--
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2.26.2
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