| Message ID | 92fc97b3db86bb0bdf610a2f76c03a96a99bfe8d.1724656120.git.ps@pks.im (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Memory leak fixes (pt.6) | expand |
Patrick Steinhardt <ps@pks.im> writes: > When appending a refspec via `refspec_append_mapped()` we leak the > result of `query_refspecs()`. The overall logic around refspec queries > is quite weird, as callers are expected to either set the `src` or `dst` > pointers, and then the (allocated) result will be in the respective > other struct member. Hmph, is it necessary to say "quite weird" for the purpose of this change? The query interface is designed to be usable to query both ways and within that constraints, I find it designed very nicely (but I do not think that is necessary to be said for the purpose of this change, either).. > As we have the `src` member set, plugging the memory leak is thus as > easy as just freeing the `dst` member. While at it, use designated > initializers to initialize the structure. In order to understand this paragraph, of course, it helps for a reader to understand that the query_refspecs() gives an answer by populating the side other than the query side, and the answers are what we want to release. > This leak was exposed by t5516, but fixing it is not sufficient to make > the whole test suite leak free. > > Signed-off-by: Patrick Steinhardt <ps@pks.im> > --- > builtin/push.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/builtin/push.c b/builtin/push.c > index 7a67398124f..0b123eb9c1e 100644 > --- a/builtin/push.c > +++ b/builtin/push.c > @@ -72,13 +72,15 @@ static void refspec_append_mapped(struct refspec *refspec, const char *ref, > const char *branch_name; > > if (remote->push.nr) { > - struct refspec_item query; > - memset(&query, 0, sizeof(struct refspec_item)); > - query.src = matched->name; > + struct refspec_item query = { > + .src = matched->name, > + }; This is "while at it" change that does not contribute to the leak or the leakfix; the resulting code is easier to read. > if (!query_refspecs(&remote->push, &query) && query.dst) { > refspec_appendf(refspec, "%s%s:%s", > query.force ? "+" : "", > query.src, query.dst); > + free(query.dst); And this is the real fix, which looks good. Thanks. > return; > } > }
On Fri, Aug 30, 2024 at 02:59:01PM -0700, Junio C Hamano wrote: > Patrick Steinhardt <ps@pks.im> writes: > > > When appending a refspec via `refspec_append_mapped()` we leak the > > result of `query_refspecs()`. The overall logic around refspec queries > > is quite weird, as callers are expected to either set the `src` or `dst` > > pointers, and then the (allocated) result will be in the respective > > other struct member. > > Hmph, is it necessary to say "quite weird" for the purpose of this > change? The query interface is designed to be usable to query both > ways and within that constraints, I find it designed very nicely > (but I do not think that is necessary to be said for the purpose of > this change, either).. I don't quite agree that it's nicely designed -- I find it rather hard to use and reason about, and the fact that so many callsites get this interface wrong seems to indicate that there is at least some sort of truth to this assessment. But I don't mind removing this subjective opinion from the commit message. I'll do that in case I end up rerolling this patch series. Thanks! Patrick
diff --git a/builtin/push.c b/builtin/push.c index 7a67398124f..0b123eb9c1e 100644 --- a/builtin/push.c +++ b/builtin/push.c @@ -72,13 +72,15 @@ static void refspec_append_mapped(struct refspec *refspec, const char *ref, const char *branch_name; if (remote->push.nr) { - struct refspec_item query; - memset(&query, 0, sizeof(struct refspec_item)); - query.src = matched->name; + struct refspec_item query = { + .src = matched->name, + }; + if (!query_refspecs(&remote->push, &query) && query.dst) { refspec_appendf(refspec, "%s%s:%s", query.force ? "+" : "", query.src, query.dst); + free(query.dst); return; } }
When appending a refspec via `refspec_append_mapped()` we leak the result of `query_refspecs()`. The overall logic around refspec queries is quite weird, as callers are expected to either set the `src` or `dst` pointers, and then the (allocated) result will be in the respective other struct member. As we have the `src` member set, plugging the memory leak is thus as easy as just freeing the `dst` member. While at it, use designated initializers to initialize the structure. This leak was exposed by t5516, but fixing it is not sufficient to make the whole test suite leak free. Signed-off-by: Patrick Steinhardt <ps@pks.im> --- builtin/push.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)