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uci: reset uci_ptr flags when merging set operations

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In some cases, e.g. when subsequently setting multiple empty option
values, uci_set() might free the section pointer of the given reused
uci_ptr structure without zeroing it, leading to a use-after-free on
processing subsequent options.

Avoid this issue by clearing the lookup pointer flags in order to
prevent uci_set() from incorrectly branching into a uci_delete()
operation leading to the freeing of the section member.

Ref: http://lists.infradead.org/pipermail/openwrt-devel/2019-October/019592.html
Reported-by: Daniel Danzberger <daniel@dd-wrt.com>
Suggested-by: Yousong Zhou <yszhou4tech@gmail.com>
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
This commit is contained in:
Jo-Philipp Wich 2019-10-29 08:28:17 +01:00
parent 37aa9196b6
commit bd0ed25214
1 changed files with 1 additions and 0 deletions
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uci.c
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@ -817,6 +817,7 @@ rpc_uci_merge_set(struct blob_attr *opt, struct uci_ptr *ptr)
struct blob_attr *cur; struct blob_attr *cur;
int rem, rv; int rem, rv;
ptr->flags = 0;
ptr->o = NULL; ptr->o = NULL;
ptr->option = blobmsg_name(opt); ptr->option = blobmsg_name(opt);
ptr->value = NULL; ptr->value = NULL;