[PATCH] kfifo: do not allocate a fifo smaller than 2 bytes

[PATCH] kfifo: do not allocate a fifo smaller than 2 bytes

[Ahmad Fatoum]

Linux also refuses allocation of such FIFOs and if such argument indeed
passes, it's most likely a bug, so exit early.

All users of kfifo_init in barebox currently pass a fixed larger
power-of-two argument, except for TFTP, which calculates it dynamically,
but this is fixed separately. This patch is thus just to future proof.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 lib/kfifo.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/kfifo.c b/lib/kfifo.c
index fa22feb7e082..bf1ab138c6e6 100644
--- a/lib/kfifo.c
+++ b/lib/kfifo.c
@@ -50,6 +50,9 @@ struct kfifo *kfifo_alloc(unsigned int size)
 	unsigned char *buffer;
 	struct kfifo *fifo;
 
+	if (size < 2)
+		return NULL;
+
 	/*
 	 * round up to the next power of 2, since our 'let the indices
 	 * wrap' tachnique works only in this case.
-- 
2.47.3

Re: [PATCH] kfifo: do not allocate a fifo smaller than 2 bytes

[Sascha Hauer]

On Fri, 17 Apr 2026 11:36:59 +0200, Ahmad Fatoum wrote:
> Linux also refuses allocation of such FIFOs and if such argument indeed
> passes, it's most likely a bug, so exit early.
> 
> All users of kfifo_init in barebox currently pass a fixed larger
> power-of-two argument, except for TFTP, which calculates it dynamically,
> but this is fixed separately. This patch is thus just to future proof.
> 
> [...]

Applied, thanks!

[1/1] kfifo: do not allocate a fifo smaller than 2 bytes
      https://git.pengutronix.de/cgit/barebox/commit/?id=ae4696c16996 (link may not be stable)

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>