run-command: avoid close(-1) in start_command() error paths

When `start_command()` fails to set up a pipe partway through, it rolls
back by closing the pipe ends it has already opened. For descriptors
supplied by the caller rather than allocated locally, that rollback
tested `if (cmd->in)` / `if (cmd->out)` before calling close(). The
CHILD_PROCESS_INIT default of -1 ("no descriptor") is non-zero and so
passes the test, meaning a caller that sets cmd->no_stdin or
cmd->no_stdout without supplying a real fd ends up triggering close(-1)
on the error path.

The stdin-pipe failure branch a few lines above already uses the right
idiom, `if (cmd->out > 0)`, which rejects both the -1 sentinel and 0
(the parent's own standard streams). Apply it to the three remaining
rollback sites.

Reported by Coverity as CID 1049722 ("Argument cannot be negative").

Assisted-by: Opus 4.7
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Johannes Schindelin
2026-07-05 08:24:21 +00:00
committed by Junio C Hamano
parent a62c2a26fc
commit c3f89beb73

View File

@@ -706,7 +706,7 @@ int start_command(struct child_process *cmd)
failed_errno = errno;
if (need_in)
close_pair(fdin);
else if (cmd->in)
else if (cmd->in > 0)
close(cmd->in);
str = "standard output";
goto fail_pipe;
@@ -720,11 +720,11 @@ int start_command(struct child_process *cmd)
failed_errno = errno;
if (need_in)
close_pair(fdin);
else if (cmd->in)
else if (cmd->in > 0)
close(cmd->in);
if (need_out)
close_pair(fdout);
else if (cmd->out)
else if (cmd->out > 0)
close(cmd->out);
str = "standard error";
fail_pipe: