Re: [PATCH -next] Revert "evm: Fix memleak in init_desc"

From: xiujianfeng
Date: Fri Jun 10 2022 - 23:25:03 EST



在 2022/6/10 22:20, Mimi Zohar 写道:
On Fri, 2022-05-27 at 19:17 +0800, Xiu Jianfeng wrote:
This reverts commit ccf11dbaa07b328fa469415c362d33459c140a37.

Commit ccf11dbaa07b ("evm: Fix memleak in init_desc") said there is
memleak in init_desc. That may be incorrect, as we can see, tmp_tfm is
saved in one of the two global variables hmac_tfm ohr evm_tfm[hash_algo],
then if init_desc is called next time, there is no need to alloc tfm
again, so in the error path of kmalloc desc or crypto_shash_init(desc),
It is not a problem without freeing tmp_tfm.

And also that commit did not reset the global variable to NULL after
freeing tmp_tfm and this makes *tfm a dangling pointer which may cause a
UAF issue.

Signed-off-by: Xiu Jianfeng <xiujianfeng@xxxxxxxxxx>
Agreed, thanks. This was first reported by Guozihua (Scott) <
guozihua@xxxxxxxxxx>. If neither you nor Scott object, I'll add his
Reported-by tag.
Good for me,  thanks.

thanks,

Mimi





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