Re: [PATCH] nss: Fix memory leak in findLease

On Mon, Apr 14, 2025 at 03:06:09PM +0300, Alexander Kuznetsov wrote: > path is allocated by asprintf() and must be freed later if realloc() fails or at > the end of each while() iteration > > Move the free() call out of LIBVIRT_NSS_GUEST macro and add another one if > realloc() fails > > Found by Linux Verification Center (linuxtesting.org) with Svace. > > Reported-by: Dmitry Fedin <d.fedin(a)fobos-nt.ru&gt; > Signed-off-by: Alexander Kuznetsov <kuznetsovam(a)altlinux.org&gt; > --- > tools/nss/libvirt_nss.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/tools/nss/libvirt_nss.c b/tools/nss/libvirt_nss.c > index d79a00a1b0..190cc7a3dd 100644 > --- a/tools/nss/libvirt_nss.c > +++ b/tools/nss/libvirt_nss.c > @@ -141,8 +141,11 @@ findLease(const char *name, > goto cleanup; > > tmpLease = realloc(leaseFiles, sizeof(char *) * (nleaseFiles + 1)); > - if (!tmpLease) > + if (!tmpLease) { > + free(path); > goto cleanup; > + } > + > leaseFiles = tmpLease; > leaseFiles[nleaseFiles++] = path; > #if defined(LIBVIRT_NSS_GUEST) > @@ -155,8 +158,8 @@ findLease(const char *name, > free(path); > goto cleanup; > } > - free(path); > #endif /* LIBVIRT_NSS_GUEST */ > + free(path); AFAICT in this 'else if' branch, 'path' is only allocated inside the 'LIBVIRT_NSS_GUEST' condition, so movnig the free outside is pointless. Rather than adding more "free" calls, I think this code would be improved by declaring 'path' with "g_autofree" and using g_steal_pointer when assigning it to 'leaseFiles[nleaseFiles++]', then existing 'free' calls can be removed.