musl - musl - an implementation of the standard library for Linux-based systems

musl - an implementation of the standard library for Linux-based systems

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author	Rich Felker <dalias@aerifal.cx>	2025年02月12日 17:06:30 -0500
committer	Rich Felker <dalias@aerifal.cx>	2025年02月12日 17:06:30 -0500
commit	c47ad25ea3b484e10326f933e927c0bc8cded3da (patch)
tree	2c1d63ea8a44fdba4477fcb505ab3a357a20bb08 /src
parent	4c4f15dae57125e5b65b9690901384ae501d38e2 (diff)
download	musl-c47ad25ea3b484e10326f933e927c0bc8cded3da.tar.gz

iconv: harden UTF-8 output code path against input decoder bugs

the UTF-8 output code was written assuming an invariant that iconv's decoders only emit valid Unicode Scalar Values which wctomb can encode successfully, thereby always returning a value between 1 and 4. if this invariant is not satisfied, wctomb returns (size_t)-1, and the subsequent adjustments to the output buffer pointer and remaining output byte count overflow, moving the output position backwards, potentially past the beginning of the buffer, without storing any bytes.

Diffstat (limited to 'src')

-rw-r--r--

src/locale/iconv.c

1 files changed, 4 insertions, 0 deletions

diff --git a/src/locale/iconv.c b/src/locale/iconv.c
index 008c93f0..52178950 100644
--- a/src/locale/iconv.c
+++ b/src/locale/iconv.c

@@ -545,6 +545,10 @@ size_t iconv(iconv_t cd, char **restrict in, size_t *restrict inb, char **restri

if (*outb < k) goto toobig;

memcpy(*out, tmp, k);

} else k = wctomb_utf8(*out, c);

+ /* This failure condition should be unreachable, but

+ * is included to prevent decoder bugs from translating

+ * into advancement outside the output buffer range. */

+ if (k>4) goto ilseq;

*out += k;

*outb -= k;

break;

generated by cgit v1.2.1 (git 2.18.0) at 2025年09月11日 00:19:43 +0000