@matheusbsbs / matheus-bagliano / commits / 5ab83521cf

reftable/merged: fix zero-sized allocation when there are no readers

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> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Patrick Steinhardt committed Dec 22, 2024 at 08:24 UTC 5ab83521cfe687e4295f5748f2c5d2aa7477efe5

1 file changed +7 -5

reftable/merged.c

+7 -5

@@ -238,14 +238,16 @@ int merged_table_init_iter(struct reftable_merged_table *mt,

238 struct reftable_iterator *it,

239 uint8_t typ)

240 {

241 - struct merged_subiter *subiters;

241 + struct merged_subiter *subiters = NULL;

242 struct merged_iter *mi = NULL;

243 int ret;

244

245 - REFTABLE_CALLOC_ARRAY(subiters, mt->readers_len);

246 - if (!subiters) {

247 - ret = REFTABLE_OUT_OF_MEMORY_ERROR;

248 - goto out;

245 + if (mt->readers_len) {

246 + REFTABLE_CALLOC_ARRAY(subiters, mt->readers_len);

247 + if (!subiters) {

248 + ret = REFTABLE_OUT_OF_MEMORY_ERROR;

249 + goto out;

250 + }

251 }

252

253 for (size_t i = 0; i < mt->readers_len; i++) {