libafs: don't call afs_PutDCache(NULL) in afs_GetDownD()

It's possible for an eviction candidate to be omitted by the small
for loop (around line 670), leaving its reference in victimDCs
set to NULL.  In the big for loop that follows, don't call
afs_PutDCache() when we hit one.

Found-by: clang static analyzer with help from AFS_NONNULL
Reviewed-on: http://gerrit.openafs.org/5260
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 10d27341808be41b29fbcc09b8bd7523c3b7a541)

Change-Id: I4ff3ab9a57c1c48be0f7533ab3adb1e4b6ababf9
Reviewed-on: http://gerrit.openafs.org/5263
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>

diff --git a/src/afs/afs_dcache.c b/src/afs/afs_dcache.c
index 038057eaf3d37da7e21e75aeaf7b32a8d764363f..41b68073a7a111df0353e881177fdf5dcbaf40b1 100644 (file)
--- a/src/afs/afs_dcache.c
+++ b/src/afs/afs_dcache.c
@@ -837,7 +837,8 @@ afs_GetDownD(int anumber, int *aneedSpace, afs_int32 buckethint)
                    j = 1;      /* we reclaimed at least one victim */
                }
            }
-           afs_PutDCache(tdc);
+           if (tdc)
+               afs_PutDCache(tdc);
        }                       /* end of for victims loop */
 
        if (phase < 5) {