linux-kernel - Explanation on Uninitialized Variable bio in blk_rq_prep

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Message-Id: <20241004141037.43277-1-surajsonawane0215@gmail.com>
Date: Fri,  4 Oct 2024 19:40:37 +0530
From: SurajSonawane2415 <surajsonawane0215@...il.com>
To: hch@...radead.org
Cc: axboe@...nel.dk,
	linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	surajsonawane0215@...il.com
Subject: Explanation on Uninitialized Variable bio in blk_rq_prep_clone

Explaination of how bio could be used uninitialized in this function:

In the function blk_rq_prep_clone, the variable bio is declared but can remain uninitialized 
if the allocation with bio_alloc_clone fails. This can lead to undefined behavior when the 
function attempts to free bio in the error handling section using bio_put(bio). 
By initializing bio to NULL at declaration, we ensure that the cleanup code will only 
interact with bio if it has been successfully allocated.

Best regards,
Suraj Sonawane