From 5874510faaf3cbd0bb112aaacab9f225002beed1 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Tue, 8 Nov 2016 23:44:51 +0000 Subject: [PATCH] Fix rpcgen buffer overrun (bug 20790). Building with GCC 7 produces an error building rpcgen: rpc_parse.c: In function 'get_prog_declaration': rpc_parse.c:543:25: error: may write a terminating nul past the end of the destination [-Werror=format-length=] sprintf (name, "%s%d", ARGNAME, num); /* default name of argument */ ~~~~^ rpc_parse.c:543:5: note: format output between 5 and 14 bytes into a destination of size 10 sprintf (name, "%s%d", ARGNAME, num); /* default name of argument */ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ That buffer overrun is for the case where the .x file declares a program with a million arguments. The strcpy two lines above can generate a buffer overrun much more simply for a long argument name. The limit on length of line read by rpcgen (MAXLINESIZE == 1024) provides a bound on the buffer size needed, so this patch just changes the buffer size to MAXLINESIZE to avoid both possible buffer overruns. A testcase is added that rpcgen does not crash with a 500-character argument name, where it previously crashed. It would not at all surprise me if there are many other ways of crashing rpcgen with either valid or invalid input; fuzz testing would likely find various such bugs, though I don't think they are that important to fix (rpcgen is not that likely to be used with untrusted .x files as input). (As well as fuzz-findable bugs there are probably also issues when various int variables get overflowed on very large input.) The test infrastructure for rpcgen-not-crashing tests would need extending if tests are to be added for cases where rpcgen should produce an error, as opposed to cases where it should succeed. Tested for x86_64 and x86. [BZ #20790] * sunrpc/rpc_parse.c (get_prog_declaration): Increase buffer size to MAXLINESIZE. * sunrpc/bug20790.x: New file. * sunrpc/Makefile [$(run-built-tests) = yes] (rpcgen-tests): New variable. [$(run-built-tests) = yes] (tests-special): Add $(rpcgen-tests). [$(run-built-tests) = yes] ($(rpcgen-tests)): New rule. --- ChangeLog | 9 +++++++++ sunrpc/Makefile | 11 +++++++++++ sunrpc/bug20790.x | 1 + sunrpc/rpc_parse.c | 2 +- 4 files changed, 22 insertions(+), 1 deletion(-) create mode 100644 sunrpc/bug20790.x diff --git a/sunrpc/Makefile b/sunrpc/Makefile index 789ef423e5..99e5c3ccf8 100644 --- a/sunrpc/Makefile +++ b/sunrpc/Makefile @@ -103,6 +103,11 @@ ifeq ($(have-thread-library),yes) xtests += thrsvc endif +ifeq ($(run-built-tests),yes) +rpcgen-tests := $(objpfx)bug20790.out +tests-special += $(rpcgen-tests) +endif + headers += $(rpcsvc:%.x=rpcsvc/%.h) extra-libs := librpcsvc extra-libs-others := librpcsvc # Make it in `others' pass, not `lib' pass. @@ -225,3 +230,9 @@ endif endif $(objpfx)thrsvc: $(common-objpfx)linkobj/libc.so $(shared-thread-library) + +ifeq ($(run-built-tests),yes) +$(rpcgen-tests): $(objpfx)%.out: %.x $(objpfx)rpcgen + $(built-program-cmd) -c $< -o $@; \ + $(evaluate-test) +endif diff --git a/sunrpc/bug20790.x b/sunrpc/bug20790.x new file mode 100644 index 0000000000..a00c9b3830 --- /dev/null +++ b/sunrpc/bug20790.x @@ -0,0 +1 @@ +program TPROG { version TVERS { int FUNC(int aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa) = 1; } = 1; } = 1; diff --git a/sunrpc/rpc_parse.c b/sunrpc/rpc_parse.c index 1a1df6d8c2..505a6554cf 100644 --- a/sunrpc/rpc_parse.c +++ b/sunrpc/rpc_parse.c @@ -521,7 +521,7 @@ static void get_prog_declaration (declaration * dec, defkind dkind, int num /* arg number */ ) { token tok; - char name[10]; /* argument name */ + char name[MAXLINESIZE]; /* argument name */ if (dkind == DEF_PROGRAM) { -- 2.11.0