Re: [PATCH] net: sched: gred: potential dereference of null pointer
flat view
From: Jakub Kicinski <kuba@kernel.org>
Date: 2021-12-09 02:36:15
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On Thu, 9 Dec 2021 10:13:46 +0800 Jiasheng Jiang wrote:
The return value of kzalloc() needs to be checked.
To avoid use of null pointer in gred_change_vq() in case
of the failure of alloc.
Fixes: 869aa41044b0 ("sch_gred: prefer GFP_KERNEL allocations")
Signed-off-by: Jiasheng Jiang <redacted>I don't see how. Please explain in more detail. gred_change_vq() gets a pointer to a pointer and checks if its values is NULL.
quoted hunk ↗ jump to hunk
diff --git a/net/sched/sch_gred.c b/net/sched/sch_gred.c index f4132dc25ac0..c0d355281baf 100644 --- a/net/sched/sch_gred.c +++ b/net/sched/sch_gred.c@@ -697,6 +697,8 @@ static int gred_change(struct Qdisc *sch, struct nlattr *opt, } prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL); + if (!prealloc) + return -ENOMEM; sch_tree_lock(sch); err = gred_change_vq(sch, ctl->DP, ctl, prio, stab, max_P, &prealloc,