38 lines
1.3 KiB
Diff
38 lines
1.3 KiB
Diff
From c47ad25ea3b484e10326f933e927c0bc8cded3da Mon Sep 17 00:00:00 2001
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From: Rich Felker <dalias@aerifal.cx>
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Date: Wed, 12 Feb 2025 17:06:30 -0500
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Subject: [PATCH] iconv: harden UTF-8 output code path against input decoder
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bugs
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the UTF-8 output code was written assuming an invariant that iconv's
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decoders only emit valid Unicode Scalar Values which wctomb can encode
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successfully, thereby always returning a value between 1 and 4.
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if this invariant is not satisfied, wctomb returns (size_t)-1, and the
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subsequent adjustments to the output buffer pointer and remaining
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output byte count overflow, moving the output position backwards,
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potentially past the beginning of the buffer, without storing any
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bytes.
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---
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src/locale/iconv.c | 4 ++++
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1 file changed, 4 insertions(+)
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diff --git a/src/locale/iconv.c b/src/locale/iconv.c
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index 008c93f0..52178950 100644
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--- a/src/locale/iconv.c
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+++ b/src/locale/iconv.c
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@@ -545,6 +545,10 @@ size_t iconv(iconv_t cd, char **restrict in, size_t *restrict inb, char **restri
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if (*outb < k) goto toobig;
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memcpy(*out, tmp, k);
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} else k = wctomb_utf8(*out, c);
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+ /* This failure condition should be unreachable, but
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+ * is included to prevent decoder bugs from translating
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+ * into advancement outside the output buffer range. */
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+ if (k>4) goto ilseq;
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*out += k;
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*outb -= k;
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break;
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--
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2.21.0
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