[v2,2/3] add support for -Wmemcpy-max-count

Commit Message

Luc Van Oostenryck June 3, 2017, 7:47 a.m. UTC

sparse will warn if memcpy() (or memset(), copy_from_user(),
copy_to_user()) is called with a very large static byte-count.

But this warning is given unconditionaly while there are projects
where this warning may not be not desired.

Change this by making this warning conditional on a new warning
flag: -W[no-]memcpy-max-count

Signed-off-by: Luc Van Oostenryck <[e-mail]>
---
 lib.c    | 2 ++
 lib.h    | 1 +
 sparse.1 | 8 ++++++++
 sparse.c | 3 ++-
 4 files changed, 13 insertions(+), 1 deletion(-)

Patch

diff --git a/lib.c b/lib.c
index e1e6a1cbf..90fd2b494 100644
--- a/lib.c
+++ b/lib.c
@@ -229,6 +229,7 @@  int Wdo_while = 0;
 int Winit_cstring = 0;
 int Wenum_mismatch = 1;
 int Wsparse_error = 0;
+int Wmemcpy_max_count = 1;
 int Wnon_pointer_null = 1;
 int Wold_initializer = 1;
 int Wone_bit_signed_bitfield = 1;
@@ -506,6 +507,7 @@  static const struct warning {
 	{ "enum-mismatch", &Wenum_mismatch },
 	{ "sparse-error", &Wsparse_error },
 	{ "init-cstring", &Winit_cstring },
+	{ "memcpy-max-count", &Wmemcpy_max_count },
 	{ "non-pointer-null", &Wnon_pointer_null },
 	{ "old-initializer", &Wold_initializer },
 	{ "one-bit-signed-bitfield", &Wone_bit_signed_bitfield },
diff --git a/lib.h b/lib.h
index 2c8529f93..8090fe247 100644
--- a/lib.h
+++ b/lib.h
@@ -116,6 +116,7 @@  extern int Wdo_while;
 extern int Wenum_mismatch;
 extern int Wsparse_error;
 extern int Winit_cstring;
+extern int Wmemcpy_max_count;
 extern int Wnon_pointer_null;
 extern int Wold_initializer;
 extern int Wone_bit_signed_bitfield;
diff --git a/sparse.1 b/sparse.1
index c924b3a59..df3c7f442 100644
--- a/sparse.1
+++ b/sparse.1
@@ -210,6 +210,14 @@  trouble.
 Sparse does not issue these warnings by default.
 .
 .TP
+.B \-Wmemcpy\-max\-count
+Warn about call of \fBmemcpy()\fR, \fBmemset()\fR, \fBcopy_from_user()\fR, or
+\fBcopy_to_user()\fR with a large compile-time byte count.
+
+Sparse issues these warnings by default. To turn them off, use
+\fB\-Wno\-memcpy\-max\-count\fR.
+.
+.TP
 .B \-Wnon\-pointer\-null
 Warn about the use of 0 as a NULL pointer.
 
diff --git a/sparse.c b/sparse.c
index 1cb90e20d..aa5979f1a 100644
--- a/sparse.c
+++ b/sparse.c
@@ -153,7 +153,8 @@  static void check_byte_count(struct instruction *insn, pseudo_t count)
 		return;
 	if (count->type == PSEUDO_VAL) {
 		unsigned long long val = count->value;
-		if (val > 100000ULL)
+		if (Wmemcpy_max_count && val > 100000ULL)
+
 			warning(insn->pos, "%s with byte count of %llu",
 				show_ident(insn->func->sym->ident), val);
 		return;