Re: [PATCH] io_uring: fix xa_alloc_cycle() error return value check

[Jens Axboe <axboe@kernel.dk>]

On 8/20/21 2:57 PM, Jens Axboe wrote:
> We currently check for ret != 0 to indicate error, but '1' is a valid
> return and just indicates that the allocation succeeded with a wrap.
> Correct the check to be for < 0, like it was before the xarray
> conversion.
> 
> Cc: stable@vger.kernel.org
> Fixes: 61cf93700fe6 ("io_uring: Convert personality_idr to XArray")
> Signed-off-by: Jens Axboe <axboe@kernel.dk>

Gah, included a debug patch, not the fix. Here's the right one.

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 979941bcd15a..a2e20a6fbfed 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -9843,10 +9843,11 @@ static int io_register_personality(struct io_ring_ctx *ctx)
 
 	ret = xa_alloc_cyclic(&ctx->personalities, &id, (void *)creds,
 			XA_LIMIT(0, USHRT_MAX), &ctx->pers_next, GFP_KERNEL);
-	if (!ret)
-		return id;
-	put_cred(creds);
-	return ret;
+	if (ret < 0) {
+		put_cred(creds);
+		return ret;
+	}
+	return id;
 }
 
 static int io_register_restrictions(struct io_ring_ctx *ctx, void __user *arg,

-- 
Jens Axboe