[PATCH] gunzip: Fix len parameter in function signature

[Heinrich Schuchardt]

Am 28. Januar 2026 00:51:35 MEZ schrieb Marek Vasut <marek.vasut+renesas at mailbox.org>:
>The only call site of gzwrite() is cmd/unzip.c do_gzwrite(), where
>the 'len' parameter passed to gzwrite(..., len, ...) function is of
>type unsigned long. This usage is correct, the 'len' parameter is
>an unsigned integer, and the gzwrite() function currently supports
>input data 'len' of up to 4 GiB - 1 .
>
>The function signature of gzwrite() function in both include/gzip.h
>and lib/gunzip.c does however list 'len' as signed integer, which
>is not correct, and ultimatelly limits the implementation to only
>2 GiB input data 'len' .
>
>Fix this, update gzwrite() function parameter 'len' data type to
>unsigned long consistently in include/gzip.h and lib/gunzip.c .
>
>Furthermore, update gzwrite() function 'szwritebuf' parameter in
>lib/gunzip.c from 'unsigned long' to 'ulong' to be synchronized
>with include/gzip.h .
>
>Since the gzwrite() function currently surely only supports input
>data size of 4 GiB - 1, add input data size check. The limitation
>comes from the current use of zlib z_stream .avail_in parameter,
>to which the gzwrite() function sets the entire input data size,
>and which is of unsigned int type, which cannot accept any number
>beyond 4 GiB - 1. This limitation will be removed in future commit.
>
>Reported-by: Yuya Hamamachi <yuya.hamamachi.sx at renesas.com>
>Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
>---
>Cc: Alexander Graf <agraf at csgraf.de>
>Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
>Cc: Ilias Apalodimas <ilias.apalodimas at linaro.org>
>Cc: Jerome Forissier <jerome at forissier.org>
>Cc: Mattijs Korpershoek <mkorpershoek at kernel.org>
>Cc: Neil Armstrong <neil.armstrong at linaro.org>
>Cc: Peng Fan <peng.fan at nxp.com>
>Cc: Quentin Schulz <quentin.schulz at cherry.de>
>Cc: Simon Glass <sjg at chromium.org>
>Cc: Tom Rini <trini at konsulko.com>
>Cc: Yuya Hamamachi <yuya.hamamachi.sx at renesas.com>
>Cc: u-boot at lists.denx.de
>---
> include/gzip.h |  4 ++--
> lib/gunzip.c   | 13 ++++++++-----
> 2 files changed, 10 insertions(+), 7 deletions(-)
>
>diff --git a/include/gzip.h b/include/gzip.h
>index 304002ffc42..5396e3ffec7 100644
>--- a/include/gzip.h
>+++ b/include/gzip.h
>@@ -77,8 +77,8 @@ void gzwrite_progress_finish(int retcode, ulong totalwritten, ulong totalsize,
>  *		for files under 4GiB
>  * Return: 0 if OK, -1 on error
> p */
>-int gzwrite(unsigned char *src, int len, struct blk_desc *dev, ulong szwritebuf,
>-	    ulong startoffs, ulong szexpected);
>+int gzwrite(unsigned char *src, unsigned long len, struct blk_desc *dev,
>+	    ulong szwritebuf, ulong startoffs, ulong szexpected);

Ulong and unsigned long are essentially the same but using both in one function signature looks weird.

I would prefer size_t for the size of objects in memory and off_t for file sizes and positions in files.

Please, consider adjusting startoffs and szexpected, too.

> 
> /**
>  * gzip()- Compress data into a buffer using the gzip algorithm
>diff --git a/lib/gunzip.c b/lib/gunzip.c
>index a05dcde9a75..040450c0e79 100644
>--- a/lib/gunzip.c
>+++ b/lib/gunzip.c
>@@ -116,11 +116,8 @@ void gzwrite_progress_finish(int returnval,
> 	}
> }
> 
>-int gzwrite(unsigned char *src, int len,
>-	    struct blk_desc *dev,
>-	    unsigned long szwritebuf,
>-	    ulong startoffs,
>-	    ulong szexpected)
>+int gzwrite(unsigned char *src, unsigned long len, struct blk_desc *dev,
>+	    ulong szwritebuf, ulong startoffs, ulong szexpected)

ditto

> {
> 	int i, flags;
> 	z_stream s;
>@@ -133,6 +130,12 @@ int gzwrite(unsigned char *src, int len,
> 	u32 payload_size;
> 	int iteration = 0;
> 
>+	if (len > 0xffffffff) {
>+		printf("%s: input size over 4 GiB in size not supported\n",
>+		       __func__);

Please, use log_err() for error output.

Best regards

Heinrich

>+		return -1;
>+	}
>+
> 	if (!szwritebuf ||
> 	    (szwritebuf % dev->blksz) ||
> 	    (szwritebuf < dev->blksz)) {