[PATCH v2 2/4] reftable/merged: fix zero-sized allocation when there are no readers
- From
Patrick Steinhardt <ps@pks.im>
- Date
- Dec 22, 2024, 07:24 UTC
- Message-ID
- <20241222-b4-pks-reftable-oom-fix-without-readers-v2-2-19550090d15a@pks.im>
- In-Reply-To
- <20241222-b4-pks-reftable-oom-fix-without-readers-v2-0-19550090d15a@pks.im>
It was reported [1] that Git started to fail with an out-of-memory error when initializing repositories with the reftable backend on NonStop platforms. A bisect led to 802c0646ac (reftable/merged: handle allocation failures in `merged_table_init_iter()`, 2024-10-02), which changed how we allocate memory when initializing a merged table.
The root cause of this seems to be that NonStop returns a `NULL` pointer when doing a zero-sized allocation. This would've already happened before the above change, but we never noticed because we did not check the result. Now we do notice and thus return an out-of-memory error to the caller.
Fix the issue by skipping the allocation altogether in case there are no readers.
[1]: <00ad01db5017$aa9ce340$ffd6a9c0$@nexbridge.com>
Reported-by: Randall S. Becker <rsbecker@nexbridge.com> Signed-off-by: Patrick Steinhardt <ps@pks.im> --- reftable/merged.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/reftable/merged.c b/reftable/merged.c index bb0836e3443271f9c0d5ba5582c78694d437ddc2..e72b39e178d4dec6ddfca970b5af71b71431397a 100644 --- a/reftable/merged.c +++ b/reftable/merged.c @@ -240,14 +240,16 @@ int merged_table_init_iter(struct reftable_merged_table *mt, struct reftable_iterator *it, uint8_t typ) { - struct merged_subiter *subiters; + struct merged_subiter *subiters = NULL; struct merged_iter *mi = NULL; int ret; - REFTABLE_CALLOC_ARRAY(subiters, mt->readers_len); - if (!subiters) { - ret = REFTABLE_OUT_OF_MEMORY_ERROR; - goto out; + if (mt->readers_len) { + REFTABLE_CALLOC_ARRAY(subiters, mt->readers_len); + if (!subiters) { + ret = REFTABLE_OUT_OF_MEMORY_ERROR; + goto out; + } } for (size_t i = 0; i < mt->readers_len; i++) {
-- 2.48.0.rc0.184.g0fc57dec57.dirty