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qga: Fix memory leak when output stream is unused

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If capture-output is requested but one of the channels goes unused (eg.
we attempt to capture stderr but the command never writes to stderr), we
can leak memory.

guest_exec_output_watch() is (from what I understand) unconditionally
called for both streams if output capture is requested. The first call
will always pass the `p->size == p->length` check b/c both values are
0. Then GUEST_EXEC_IO_SIZE bytes will be allocated for the stream.

But when we reap the exited process there's a `gei->err.length > 0`
check to actually free the buffer. Which does not get run if the command
doesn't write to the stream.

Fix by making free() unconditional.

Reviewed-by: Konstantin Kostiuk <kkostiuk@redhat.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>
This commit is contained in:
Daniel Xu 2023-10-01 12:38:25 -06:00 committed by Konstantin Kostiuk
parent 99bb31585c
commit d6f67b83b8
1 changed files with 2 additions and 2 deletions
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4
qga/commands.c
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@ -206,15 +206,15 @@ GuestExecStatus *qmp_guest_exec_status(int64_t pid, Error **errp)
#endif
if (gei->out.length > 0) {
ges->out_data = g_base64_encode(gei->out.data, gei->out.length);
g_free(gei->out.data);
ges->has_out_truncated = gei->out.truncated;
}
g_free(gei->out.data);
if (gei->err.length > 0) {
ges->err_data = g_base64_encode(gei->err.data, gei->err.length);
g_free(gei->err.data);
ges->has_err_truncated = gei->err.truncated;
}
g_free(gei->err.data);
QTAILQ_REMOVE(&guest_exec_state.processes, gei, next);
g_free(gei);