https://llvm.org/bugs/show_bug.cgi?id=25991
Bug ID: 25991
Summary: libFuzzer fails to load corpus if filesystem does not
provide d_type
Product: new-bugs
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: new bugs
Assignee: unassignedb...@nondot.org
Reporter: jack.ll...@gmail.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
With latest (trunk) libFuzzer I ran into a problem fuzzing processes on my
desktop machine. Running the fuzzer against a corpus directory, it would
repeatedly show no units loaded even though it was saving finds to the same
directory.
It turned out to be due to this loop in FuzzerIO.cpp
while (auto E = readdir(D)) {
if (E->d_type == DT_REG || E->d_type == DT_LNK)
V.push_back(E->d_name);
}
The Linux man page says d_type is not set for some filesystems, this apparently
includes XFS when running over dm-crypt. This caused this loop to appear to
load the corpus but actually silently skip all the files provided.
I fixed it locally by adding to this loop (from memory here):
else if(E->d_type == DT_UNKNOWN && strcmp(E->d_name, ".") != 0 &&
strcmp(E->d_name, "..") != 0)
V.push_back(E->d_name);
at which point I could stop and restart my fuzzers and everything seemed to
work.
Let me know if there is any additional information I can provide, and thanks
for a great piece of software.
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