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-rw-r--r--util/format.lua7
1 files changed, 6 insertions, 1 deletions
diff --git a/util/format.lua b/util/format.lua
index 533f3a82..09369da4 100644
--- a/util/format.lua
+++ b/util/format.lua
@@ -1,6 +1,9 @@
--
--- A string.format wrapper that gracefully handles invalid arguments
+-- A string.format wrapper that gracefully handles invalid arguments since
+-- certain format string and argument combinations may casue errors or other
+-- issues like log spoofing
--
+-- Provides some protection from e.g. CAPEC-135, CWE-117, CWE-134, CWE-93
local tostring = tostring;
local unpack = table.unpack or unpack; -- luacheck: ignore 113/unpack
@@ -109,6 +112,8 @@ local function format(formatstring, ...)
if not valid_utf8(arg) then
option = "q";
elseif option ~= "q" then -- gets fully escaped in the next block
+ -- Prevent funny things with ASCII control characters and ANSI escape codes (CWE-117)
+ -- Also ensure embedded newlines can't look like another log line (CWE-93)
args[i] = arg:gsub("[%z\1-\8\11-\31\127]", control_symbols):gsub("\n\t?", "\n\t");
return spec;
end