debuginfod-client: correct invalid free() in failed ima path

debuginfod-find with a failed signature configuration was found on f41
glibc (2.40) to sometimes leave invalid addresses in a sscanf("%ms", &ptr)
pointer in case of error, leading to an invalid free() during cleanup.
We now clear that ptr manually, making valgrind happy.  Unclear why this
hasn't shown up in testsuite testing.

==1098106== Invalid free() / delete / delete[] / realloc()
==1098106==    at 0x4844B83: free (vg_replace_malloc.c:989)
==1098106==    by 0x49647A2: ??? (in /usr/lib64/libdebuginfod-0.192.so)
==1098106==    by 0x401528: main (debuginfod-find.c:209)
==1098106==  Address 0xc8 is not stack'd, malloc'd or (recently) free'd

Signed-off-by: Frank Ch. Eigler <fche@redhat.com>

diff --git a/debuginfod/debuginfod-client.c b/debuginfod/debuginfod-client.c
index d89beae93ea1d8f6b3aa62017c1b404919d6d79d..4152b06a135fdf8a45be5dcf97df3dd5d488fb43 100644 (file)
--- a/debuginfod/debuginfod-client.c
+++ b/debuginfod/debuginfod-client.c
@@ -1599,6 +1599,7 @@ debuginfod_validate_imasig (debuginfod_client *c, int fd)
     if (!hdr_ima_sig || 1 != sscanf(hdr_ima_sig + strlen("x-debuginfod-imasignature:"), "%ms", &sig_buf))
     {
       rc = -ENODATA;
+      sig_buf = NULL; // f41 glibc may litter here in case of sscanf error
       goto exit_validate;
     }
     if (strlen(sig_buf) > MAX_SIGNATURE_SIZE) // reject if too long