Re: [PATCH] tpm: fix crash when FD >= 1024

[Stefan Berger]

On 9/11/23 07:36, marcandre.lur...@redhat.com wrote:
From: Marc-Andr޸ Lureau <marcandre.lur...@redhat.com>

Replace select() with poll() to fix a crash when QEMU has a large number
of FDs.

Fixes:
https://bugzilla.redhat.com/show_bug.cgi?id=2020133

The description there seems wrong. It's a limit of the POSIX API not the 
vTPM device driver.


Signed-off-by: Marc-Andr޸ Lureau <marcandre.lur...@redhat.com>

Reviewed-by: Stefan Berger <stef...@linux.ibm.com>



---
  backends/tpm/tpm_util.c | 12 +++---------
  1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/backends/tpm/tpm_util.c b/backends/tpm/tpm_util.c
index a6e6d3e72f..5f4c9f5b6f 100644
--- a/backends/tpm/tpm_util.c
+++ b/backends/tpm/tpm_util.c
@@ -112,12 +112,9 @@ static int tpm_util_request(int fd,
                              void *response,
                              size_t responselen)
  {
-    fd_set readfds;
+    GPollFD fds[1] = { {.fd = fd, .events = G_IO_IN } };
      int n;
-    struct timeval tv = {
-        .tv_sec = 1,
-        .tv_usec = 0,
-    };
+    int timeout = 1000;

      n = write(fd, request, requestlen);
      if (n < 0) {
@@ -127,11 +124,8 @@ static int tpm_util_request(int fd,
          return -EFAULT;
      }

-    FD_ZERO(&readfds);
-    FD_SET(fd, &readfds);
-
      /* wait for a second */
-    n = select(fd + 1, &readfds, NULL, NULL, &tv);
+    n = RETRY_ON_EINTR(g_poll(fds, 1, timeout));
      if (n != 1) {
          return -errno;
      }