linux-kernel - [PATCH v2] fs/eventfd.c: Check error number after calling ida_simple

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Message-Id: <20220112065135.692325-1-jiasheng@iscas.ac.cn>
Date:   Wed, 12 Jan 2022 14:51:35 +0800
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     ebiggers@...nel.org
Cc:     viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: [PATCH v2] fs/eventfd.c: Check error number after calling ida_simple_get

As the possible failure of the allocation, the ida_simple_get() will
return error number.
And then ctx->id will be printed in eventfd_show_fdinfo().
Therefore, it should be better to check it and return error if fails,
like the other allocation.

Fixes: b556db17b0e7 ("eventfd: present id to userspace via fdinfo")
Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
---
Changelog

v1 -> v2

* Change 1. Correct the check condition.
---
 fs/eventfd.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/eventfd.c b/fs/eventfd.c
index 3627dd7d25db..3e226f6cbe4f 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -424,6 +424,10 @@ static int do_eventfd(unsigned int count, int flags)
 	ctx->count = count;
 	ctx->flags = flags;
 	ctx->id = ida_simple_get(&eventfd_ida, 0, 0, GFP_KERNEL);
+	if (ctx->id < 0) {
+		fd = ctx->id;
+		goto err;
+	}
 
 	flags &= EFD_SHARED_FCNTL_FLAGS;
 	flags |= O_RDWR;
-- 
2.25.1