linux-kernel - Re: [PATCH v2] smb: client: fix possible double free in smb2_set

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Message-ID: <c0afa02b-991c-4601-bacb-13ace9cb96f2@stanley.mountain>
Date: Tue, 15 Oct 2024 13:45:28 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Su Hui <suhui@...china.com>
Cc: sfrench@...ba.org, pc@...guebit.com, ronniesahlberg@...il.com,
	sprasad@...rosoft.com, stfrench@...rosoft.com, tom@...pey.com,
	bharathsm@...rosoft.com, nathan@...nel.org, ndesaulniers@...gle.com,
	morbo@...gle.com, justinstitt@...gle.com,
	linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org,
	linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH v2] smb: client: fix possible double free in smb2_set_ea()

On Tue, Oct 15, 2024 at 06:20:37PM +0800, Su Hui wrote:
> Clang static checker(scan-build) warning：
> fs/smb/client/smb2ops.c:1304:2: Attempt to free released memory.
>  1304 |         kfree(ea);
>       |         ^~~~~~~~~
> 
> There is a double free in such case:
> 'ea is initialized to NULL' -> 'first successful memory allocation for
> ea' -> 'something failed, goto sea_exit' -> 'first memory release for ea'
> -> 'goto replay_again' -> 'second goto sea_exit before allocate memory
> for ea' -> 'second memory release for ea resulted in double free'.
> 
> Re-initialie 'ea' to NULL near to the replay_again label, it can fix this
> double free problem.
> 
> Fixes: 4f1fffa23769 ("cifs: commands that are retried should have replay flag set")
> Signed-off-by: Su Hui <suhui@...china.com>
> ---
> v2: 
> - Move 'ea = NULL' near to the replay_again label.(Dan's suggestion)

Thanks!

Reviewed-by: Dan Carpenter <dan.carpenter@...aro.org>

regards,
dan carpenter