We use add_patterns() to read .gitignore, .git/info/exclude, etc, as
well as other pattern-like files like sparse-checkout. The parser for
these uses an "int" as an index, meaning that files over 2GB will
generally cause signed integer overflow and out-of-bounds access.
This is unlikely to happen in any real files, but we do read .gitignore
files from the tree. A malicious tree could cause an out-of-bounds read
and segfault (we also write NULs over newlines, so in theory it could be
an out-of-bounds write, too, but as we go char-by-char, the first thing
that happens is trying to read a negative 2GB offset).
We could fix the most obvious issue by replacing one "int" with a
"size_t". But there are tons of "int" sprinkled throughout this code for
things like pattern lengths, number of patterns, and so on. Since nobody
would actually want a 2GB .gitignore file, an easy defensive measure is
to just refuse to parse them.
The "int" in question is in add_patterns_from_buffer(), so we could
catch it there. But by putting the checks in its two callers, we can
produce more useful error messages.
Signed-off-by: Jeff King <peff@xxxxxxxx>
---
Just something I noticed while working on leaks nearby.
dir.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/dir.c b/dir.c
index f6066cc01d..914060edfd 100644
--- a/dir.c
+++ b/dir.c
@@ -30,6 +30,7 @@
#include "symlinks.h"
#include "trace2.h"
#include "tree.h"
+#include "hex.h"
/*
* Tells read_directory_recursive how a file or directory should be treated.
@@ -1148,6 +1149,12 @@ static int add_patterns(const char *fname, const char *base, int baselen,
}
}
+ if (size > INT_MAX) {
+ warning("ignoring excessively large pattern file: %s", fname);
+ free(buf);
+ return -1;
+ }
+
add_patterns_from_buffer(buf, size, base, baselen, pl);
return 0;
}
@@ -1204,6 +1211,13 @@ int add_patterns_from_blob_to_list(
if (r != 1)
return r;
+ if (size > INT_MAX) {
+ warning("ignoring excessively large pattern blob: %s",
+ oid_to_hex(oid));
+ free(buf);
+ return -1;
+ }
+
add_patterns_from_buffer(buf, size, base, baselen, pl);
return 0;
}
--
2.45.1.727.ge984192922
