tree 333da04142c48ce205024b80213cc455ab2d349f
parent e088fb3338b59536e9da2f456ba214216252653b
author Aurelien DARRAGON <adarragon@haproxy.com> 1668759449 +0100
committer Christopher Faulet <cfaulet@haproxy.com> 1669373335 +0100

BUG/MINOR: http_ana/txn: don't re-initialize txn and req var lists

In http_create_txn(): vars_init_head() was performed on both s->vars_txn
and s->var_reqres lists.

But this is wrong, these two lists are already initialized upon stream
creation in stream_new().
Moreover, between stream_new() and http_create_txn(), some variable may
be defined (e.g.: by the frontend), resulting in lists not being empty.

Because of this "extra" list initialization, already defined variables
can be lost.
This causes txn dependant code not being able to access previously defined
variables as well as memory leak because http_destroy_txn() relies on these
lists to perform the purge.

This proved to be the case when a frontend sets variables and lua sample
fetch is used in backend section as described in GH #1935.
Many thanks to Darragh O'Toole for his detailed report.

Removing extra var_init_head (x2) in http_create_txn() to fix the issue.
Adding somme comments in the code in an attempt to prevent future misuses
of s->var_reqres, and s->var_txn lists.

It should be backported in every stable version.
(This is an old bug that seems to exist since 1.6-dev6)

[cf: On 2.0 and 1.8, for the legacy HTTP code, vars_init() are used during
     the TXN cleanup, when the stream is reused. So, these calls must be
     moved from http_init_txn() to http_reset_txn() and not removed.]

(cherry picked from commit 5ad2b642625b89cdf4f5fd26a598fc480abdc806)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 61882cc68c8336016f158f74c0944e1b047c6f5f)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 2096e84463826bf88a8f59c0a1c0cf6ebd507830)
[cf: s/vars_init_head/var_init]
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>