io_uring/kbuf: fix signedness in this_len calculation

JIRA: https://issues.redhat.com/browse/RHEL-116130

commit c64eff3
Author: Qingyue Zhang <chunzhennn@qq.com>
Date:   Wed Aug 27 19:43:39 2025 +0800

    io_uring/kbuf: fix signedness in this_len calculation
    
    When importing and using buffers, buf->len is considered unsigned.
    However, buf->len is converted to signed int when committing. This can
    lead to unexpected behavior if the buffer is large enough to be
    interpreted as a negative value. Make min_t calculation unsigned.
    
    Fixes: ae98dbf ("io_uring/kbuf: add support for incremental buffer consumption")
    Co-developed-by: Suoxing Zhang <aftern00n@qq.com>
    Signed-off-by: Suoxing Zhang <aftern00n@qq.com>
    Signed-off-by: Qingyue Zhang <chunzhennn@qq.com>
    Link: https://lore.kernel.org/r/tencent_4DBB3674C0419BEC2C0C525949DA410CA307@qq.com
    Signed-off-by: Jens Axboe <axboe@kernel.dk>

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>

Author: JeffMoyer

io_uring/kbuf.c

@@ -39,7 +39,7 @@ static bool io_kbuf_inc_commit(struct io_buffer_list *bl, int len)
 		u32 this_len;
 
 		buf = io_ring_head_to_buf(bl->buf_ring, bl->head, bl->mask);
-		this_len = min_t(int, len, buf->len);
+		this_len = min_t(u32, len, buf->len);
 		buf->len -= this_len;
 		if (buf->len) {
 			buf->addr += this_len;