Re: [PATCH] fsmonitor: fix khash memory leak in do_handle_client
On 12/30/25 1:42 PM, Paul Tarjan via GitGitGadget wrote:
Show 31 quoted lines
> From: Paul Tarjan <github@paulisageek.com>
>
> The do_handle_client() function allocates a khash table to de-duplicate
> pathnames when responding to client requests. Two issues existed:
>
> 1. kh_release_str() was used instead of kh_destroy_str(). The release
> function only frees internal arrays (flags, keys, vals) but not the
> struct itself (allocated by kh_init_str via xcalloc). This caused a
> 40-byte leak per request.
>
> 2. The khash was freed mid-function rather than in the cleanup section,
> so if the worker thread was interrupted before reaching that point
> during daemon shutdown, the memory would leak.
>
> Fix both issues by:
> - Initializing shown = NULL at declaration
> - Using kh_destroy_str() which handles NULL and frees both internal
> arrays and the struct itself
> - Moving the cleanup to the cleanup section so it runs on all exit paths
>
> Signed-off-by: Claude <claude@anthropic.com>
> ---
> fsmonitor: fix khash memory leak in do_handle_client
>
> The do_handle_client() function allocates a khash table to de-duplicate
> pathnames when responding to client requests. Two issues existed:
>
> 1. kh_release_str() was used instead of kh_destroy_str(). The release
> function only frees internal arrays (flags, keys, vals) but not the
> struct itself (allocated by kh_init_str via xcalloc). This caused a
> 40-byte leak per request.
>
> 2. The khash was freed mid-function rather than in the cleanup section,
> so if the worker thread was interrupted before reaching that point
> during daemon shutdown, the memory would leak.
Really? Would an interrupted thread even reach its cleanup section?
Show 48 quoted lines
>
> Fix both issues by:
>
> * Initializing shown = NULL at declaration
> * Using kh_destroy_str() which handles NULL and frees both internal
> arrays and the struct itself
> * Moving the cleanup to the cleanup section so it runs on all exit
> paths
>
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2148%2Fptarjan%2Fclaude%2Ffix-fsmonitor-hashmap-leak-gfDCU-v1
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2148/ptarjan/claude/fix-fsmonitor-hashmap-leak-gfDCU-v1
> Pull-Request: https://github.com/git/git/pull/2148
>
> builtin/fsmonitor--daemon.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/builtin/fsmonitor--daemon.c b/builtin/fsmonitor--daemon.c
> index 242c594646..bc4571938c 100644
> --- a/builtin/fsmonitor--daemon.c
> +++ b/builtin/fsmonitor--daemon.c
> @@ -671,7 +671,7 @@ static int do_handle_client(struct fsmonitor_daemon_state *state,
> const struct fsmonitor_batch *batch;
> struct fsmonitor_batch *remainder = NULL;
> intmax_t count = 0, duplicates = 0;
> - kh_str_t *shown;
> + kh_str_t *shown = NULL;
> int hash_ret;
> int do_trivial = 0;
> int do_flush = 0;
> @@ -909,8 +909,6 @@ static int do_handle_client(struct fsmonitor_daemon_state *state,
> total_response_len += payload.len;
> }
>
> - kh_release_str(shown);
> -
> pthread_mutex_lock(&state->main_lock);
>
> if (token_data->client_ref_count > 0)
> @@ -954,6 +952,7 @@ static int do_handle_client(struct fsmonitor_daemon_state *state,
> trace2_data_intmax("fsmonitor", the_repository, "response/count/duplicates", duplicates);
>
> cleanup:
> + kh_destroy_str(shown);
> strbuf_release(&response_token);
> strbuf_release(&requested_token_id);
> strbuf_release(&payload);
>
> base-commit: 7c7698a654a7a0031f65b0ab0c1c4e438e95df60René Scharfe <l.s.r@web.de>