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Fixes for CVE-2009-2911

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This commit is contained in:
Josh Stone 2009-10-21 15:51:01 +00:00
parent a1207c104a
commit 2396d5ccc6
4 changed files with 379 additions and 1 deletions
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123
SystemTap-1.0-limit-dwarf-expression-stack-size.patch Normal file
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@ -0,0 +1,123 @@
diff --git a/dwflpp.cxx b/dwflpp.cxx
index 636cd38..c31548d 100644
--- a/dwflpp.cxx
+++ b/dwflpp.cxx
@@ -2272,7 +2272,15 @@ dwflpp::express_as_string (string prelude,
fprintf(memstream, "{\n");
fprintf(memstream, "%s", prelude.c_str());
- bool deref = c_emit_location (memstream, head, 1);
+
+ unsigned int stack_depth;
+ bool deref = c_emit_location (memstream, head, 1, &stack_depth);
+
+ // Ensure that DWARF keeps loc2c to a "reasonable" stack size
+ // 32 intptr_t leads to max 256 bytes on the stack
+ if (stack_depth > 32)
+ throw semantic_error("oversized DWARF stack");
+
fprintf(memstream, "%s", postlude.c_str());
fprintf(memstream, " goto out;\n");
diff --git a/loc2c-test.c b/loc2c-test.c
index 495a95f..ed7aa4b 100644
--- a/loc2c-test.c
+++ b/loc2c-test.c
@@ -329,11 +329,14 @@ handle_variable (Dwarf_Die *lscopes, int lnscopes, int out,
"{\n"
" intptr_t value;");
- bool deref = c_emit_location (stdout, head, 1);
+ unsigned int stack_depth;
+ bool deref = c_emit_location (stdout, head, 1, &stack_depth);
obstack_free (&pool, NULL);
- puts (store ? " return;" :
+ printf (" /* max expression stack depth %u */\n", stack_depth);
+
+ puts (store ? " return;" :
" printk (\" ---> %ld\\n\", (unsigned long) value);\n"
" return;");
diff --git a/loc2c.c b/loc2c.c
index 5d6b549..0716c7d 100644
--- a/loc2c.c
+++ b/loc2c.c
@@ -2071,7 +2071,8 @@ emit_loc_address (FILE *out, struct location *loc, unsigned int indent,
assign it to an address-sized value. */
static void
emit_loc_value (FILE *out, struct location *loc, unsigned int indent,
- const char *target, bool declare)
+ const char *target, bool declare,
+ bool *used_deref, unsigned int *max_stack)
{
if (declare)
emit ("%*s%s %s;\n", indent * 2, "", STACK_TYPE, target);
@@ -2091,6 +2092,9 @@ emit_loc_value (FILE *out, struct location *loc, unsigned int indent,
case loc_address:
case loc_value:
emit_loc_address (out, loc, indent, target);
+ *used_deref = *used_deref || loc->address.used_deref;
+ if (loc->address.stack_depth > *max_stack)
+ *max_stack = loc->address.stack_depth;
break;
}
@@ -2098,7 +2102,8 @@ emit_loc_value (FILE *out, struct location *loc, unsigned int indent,
}
bool
-c_emit_location (FILE *out, struct location *loc, int indent)
+c_emit_location (FILE *out, struct location *loc, int indent,
+ unsigned int *max_stack)
{
emit ("%*s{\n", indent * 2, "");
@@ -2134,9 +2139,11 @@ c_emit_location (FILE *out, struct location *loc, int indent)
}
bool deref = false;
+ *max_stack = 0;
if (loc->frame_base != NULL)
- emit_loc_value (out, loc->frame_base, indent, "frame_base", true);
+ emit_loc_value (out, loc->frame_base, indent, "frame_base", true,
+ &deref, max_stack);
for (; loc->next != NULL; loc = loc->next)
switch (loc->type)
@@ -2144,8 +2151,7 @@ c_emit_location (FILE *out, struct location *loc, int indent)
case loc_address:
case loc_value:
/* Emit the program fragment to calculate the address. */
- emit_loc_value (out, loc, indent + 1, "addr", false);
- deref = deref || loc->address.used_deref;
+ emit_loc_value (out, loc, indent + 1, "addr", false, &deref, max_stack);
break;
case loc_fragment:
@@ -2172,6 +2178,9 @@ c_emit_location (FILE *out, struct location *loc, int indent)
emit ("%s%*s}\n", loc->address.program, indent * 2, "");
+ if (loc->address.stack_depth > *max_stack)
+ *max_stack = loc->address.stack_depth;
+
return deref || loc->address.used_deref;
}
diff --git a/loc2c.h b/loc2c.h
index becf2d8..45d9382 100644
--- a/loc2c.h
+++ b/loc2c.h
@@ -112,6 +112,7 @@ struct location *c_translate_argument (struct obstack *,
Writes complete lines of C99, code forming a complete C block, to STREAM.
Return value is true iff that code uses the `deref' runtime macros. */
-bool c_emit_location (FILE *stream, struct location *loc, int indent);
+bool c_emit_location (FILE *stream, struct location *loc, int indent,
+ unsigned int *max_stack);
/* vim: set sw=2 ts=8 cino=>4,n-2,{2,^-2,t0,(0,u0,w1,M1 : */

62
SystemTap-1.0-limit-printf-arguments.patch Normal file
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@ -0,0 +1,62 @@
diff --git a/buildrun.cxx b/buildrun.cxx
index 100cbc4..c86a442 100644
--- a/buildrun.cxx
+++ b/buildrun.cxx
@@ -200,6 +200,9 @@ compile_pass (systemtap_session& s)
// o << "CFLAGS += -fno-unit-at-a-time" << endl;
+ // 600 bytes should be enough for anybody
+ o << "EXTRA_CFLAGS += $(call cc-option,-Wframe-larger-than=600)" << endl;
+
// Assumes linux 2.6 kbuild
o << "EXTRA_CFLAGS += -Wno-unused -Werror" << endl;
#if CHECK_POINTER_ARITH_PR5947
diff --git a/testsuite/transko/varargs.stp b/testsuite/transko/varargs.stp
new file mode 100755
index 0000000..f38309a
--- /dev/null
+++ b/testsuite/transko/varargs.stp
@@ -0,0 +1,10 @@
+#! stap -p3
+
+probe begin {
+ // PR10750 enforces at most 32 print args
+ println(1, 2, 3, 4, 5, 6, 7, 8,
+ 9, 10, 11, 12, 13, 14, 15, 16,
+ 17, 18, 19, 20, 21, 22, 23, 24,
+ 25, 26, 27, 28, 29, 30, 31, 32,
+ 33)
+}
diff --git a/testsuite/transok/varargs.stp b/testsuite/transok/varargs.stp
new file mode 100755
index 0000000..216166f
--- /dev/null
+++ b/testsuite/transok/varargs.stp
@@ -0,0 +1,9 @@
+#! stap -p3
+
+probe begin {
+ // PR10750 enforces at most 32 print args
+ println(1, 2, 3, 4, 5, 6, 7, 8,
+ 9, 10, 11, 12, 13, 14, 15, 16,
+ 17, 18, 19, 20, 21, 22, 23, 24,
+ 25, 26, 27, 28, 29, 30, 31, 32)
+}
diff --git a/translate.cxx b/translate.cxx
index 04a9247..c73a5bd 100644
--- a/translate.cxx
+++ b/translate.cxx
@@ -4151,6 +4151,11 @@ c_unparser::visit_print_format (print_format* e)
{
stmt_expr block(*this);
+ // PR10750: Enforce a reasonable limit on # of varargs
+ // 32 varargs leads to max 256 bytes on the stack
+ if (e->args.size() > 32)
+ throw semantic_error("too many arguments to print", e->tok);
+
// Compute actual arguments
vector<tmpvar> tmp;

180
SystemTap-1.0-unwind-table-size-checks.patch Normal file
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@ -0,0 +1,180 @@
diff --git a/runtime/unwind.c b/runtime/unwind.c
index 00108a3..7607770 100644
--- a/runtime/unwind.c
+++ b/runtime/unwind.c
@@ -88,7 +88,7 @@ static sleb128_t get_sleb128(const u8 **pcur, const u8 *end)
/* given an FDE, find its CIE */
static const u32 *cie_for_fde(const u32 *fde, void *unwind_data,
- int is_ehframe)
+ uint32_t table_len, int is_ehframe)
{
const u32 *cie;
@@ -118,6 +118,11 @@ static const u32 *cie_for_fde(const u32 *fde, void *unwind_data,
else
cie = unwind_data + fde[1];
+ /* Make sure address falls in the table */
+ if (((void *)cie) < ((void*)unwind_data)
+ || ((void*)cie) > ((void*)(unwind_data + table_len)))
+ return NULL;
+
if (*cie <= sizeof(*cie) + 4 || *cie >= fde[1] - sizeof(*fde)
|| (*cie & (sizeof(*cie) - 1))
|| (cie[1] != 0xffffffff && cie[1] != 0)) {
@@ -200,7 +205,8 @@ static unsigned long read_pointer(const u8 **pLoc, const void *end, signed ptrTy
return value;
}
-static signed fde_pointer_type(const u32 *cie)
+static signed fde_pointer_type(const u32 *cie, void *unwind_data,
+ uint32_t table_len)
{
const u8 *ptr = (const u8 *)(cie + 2);
unsigned version = *ptr;
@@ -212,11 +218,16 @@ static signed fde_pointer_type(const u32 *cie)
const u8 *end = (const u8 *)(cie + 1) + *cie;
uleb128_t len;
+ /* end of cie should fall within unwind table. */
+ if (((void*)end) < ((void *)unwind_data)
+ || ((void *)end) > ((void *)(unwind_data + table_len)))
+ return -1;
+
/* check if augmentation size is first (and thus present) */
if (*ptr != 'z')
return -1;
/* check if augmentation string is nul-terminated */
- if ((ptr = memchr(aug = (const void *)ptr, 0, end - ptr)) == NULL)
+ if ((ptr = memchr(aug = (const void *)ptr, 0, end - ptr)) == NULL)
return -1;
++ptr; /* skip terminator */
get_uleb128(&ptr, end); /* skip code alignment */
@@ -267,6 +278,10 @@ static void set_rule(uleb128_t reg, enum item_location where, uleb128_t value, s
}
}
+/* Limit the number of instructions we process. Arbitrary limit.
+ 512 should be enough for anybody... */
+#define MAX_CFI 512
+
static int processCFI(const u8 *start, const u8 *end, unsigned long targetLoc, signed ptrType, struct unwind_state *state)
{
union {
@@ -276,6 +291,9 @@ static int processCFI(const u8 *start, const u8 *end, unsigned long targetLoc, s
} ptr;
int result = 1;
+ if (end - start > MAX_CFI)
+ return 0;
+
dbug_unwind(1, "targetLoc=%lx state->loc=%lx\n", targetLoc, state->loc);
if (start != state->cieStart) {
state->loc = state->org;
@@ -606,10 +624,10 @@ static int unwind_frame(struct unwind_frame_info *frame,
/* found the fde, now set startLoc and endLoc */
if (fde != NULL) {
- cie = cie_for_fde(fde, table, is_ehframe);
+ cie = cie_for_fde(fde, table, table_len, is_ehframe);
if (likely(cie != NULL && cie != &bad_cie && cie != &not_fde)) {
ptr = (const u8 *)(fde + 2);
- ptrType = fde_pointer_type(cie);
+ ptrType = fde_pointer_type(cie, table, table_len);
startLoc = read_pointer(&ptr, (const u8 *)(fde + 1) + *fde, ptrType);
startLoc = adjustStartLoc(startLoc, m, s, ptrType, is_ehframe);
@@ -632,12 +650,12 @@ static int unwind_frame(struct unwind_frame_info *frame,
for (fde = table, tableSize = table_len; cie = NULL, tableSize > sizeof(*fde)
&& tableSize - sizeof(*fde) >= *fde; tableSize -= sizeof(*fde) + *fde, fde += 1 + *fde / sizeof(*fde)) {
dbug_unwind(3, "fde=%lx tableSize=%d\n", (long)*fde, (int)tableSize);
- cie = cie_for_fde(fde, table, is_ehframe);
+ cie = cie_for_fde(fde, table, table_len, is_ehframe);
if (cie == &bad_cie) {
cie = NULL;
break;
}
- if (cie == NULL || cie == &not_fde || (ptrType = fde_pointer_type(cie)) < 0)
+ if (cie == NULL || cie == &not_fde || (ptrType = fde_pointer_type(cie, table, table_len)) < 0)
continue;
ptr = (const u8 *)(fde + 2);
@@ -666,6 +684,12 @@ static int unwind_frame(struct unwind_frame_info *frame,
state.cieEnd = ptr; /* keep here temporarily */
ptr = (const u8 *)(cie + 2);
end = (const u8 *)(cie + 1) + *cie;
+
+ /* end should fall within unwind table. */
+ if (((void *)end) < table
+ || ((void *)end) > ((void *)(table + table_len)))
+ goto err;
+
frame->call_frame = 1;
if ((state.version = *ptr) != 1) {
dbug_unwind(1, "CIE version number is %d. 1 is supported.\n", state.version);
@@ -723,6 +747,11 @@ static int unwind_frame(struct unwind_frame_info *frame,
state.cieEnd = end;
end = (const u8 *)(fde + 1) + *fde;
+ /* end should fall within unwind table. */
+ if (((void*)end) < table
+ || ((void *)end) > ((void *)(table + table_len)))
+ goto err;
+
/* skip augmentation */
if (((const char *)(cie + 2))[1] == 'z') {
uleb128_t augSize = get_uleb128(&ptr, end);
diff --git a/runtime/unwind/unwind.h b/runtime/unwind/unwind.h
index 285a3a3..023ea60 100644
--- a/runtime/unwind/unwind.h
+++ b/runtime/unwind/unwind.h
@@ -143,8 +143,10 @@ static unsigned long read_pointer(const u8 **pLoc,
const void *end,
signed ptrType);
static const u32 bad_cie, not_fde;
-static const u32 *cie_for_fde(const u32 *fde, void *table, int is_ehframe);
-static signed fde_pointer_type(const u32 *cie);
+static const u32 *cie_for_fde(const u32 *fde, void *table,
+ uint32_t table_len, int is_ehframe);
+static signed fde_pointer_type(const u32 *cie,
+ void *table, uint32_t table_len);
#endif /* STP_USE_DWARF_UNWINDER */
diff --git a/translate.cxx b/translate.cxx
index bc5d615..9d456bc 100644
--- a/translate.cxx
+++ b/translate.cxx
@@ -29,6 +29,11 @@ extern "C" {
#include <elfutils/libdwfl.h>
}
+// Max unwind table size (debug or eh) per module. Somewhat arbitrary
+// limit (a bit more than twice the .debug_frame size of my local
+// vmlinux for 2.6.31.4-83.fc12.x86_64)
+#define MAX_UNWIND_TABLE_SIZE (3 * 1024 * 1024)
+
using namespace std;
struct var;
@@ -4785,6 +4790,9 @@ dump_unwindsyms (Dwfl_Module *m,
get_unwind_data (m, &debug_frame, &eh_frame, &debug_len, &eh_len, &eh_addr);
if (debug_frame != NULL && debug_len > 0)
{
+ if (debug_len > MAX_UNWIND_TABLE_SIZE)
+ throw semantic_error ("module debug unwind table size too big");
+
c->output << "#if defined(STP_USE_DWARF_UNWINDER) && defined(STP_NEED_UNWIND_DATA)\n";
c->output << "static uint8_t _stp_module_" << stpmod_idx
<< "_debug_frame[] = \n";
@@ -4802,6 +4810,9 @@ dump_unwindsyms (Dwfl_Module *m,
if (eh_frame != NULL && eh_len > 0)
{
+ if (eh_len > MAX_UNWIND_TABLE_SIZE)
+ throw semantic_error ("module eh unwind table size too big");
+
c->output << "#if defined(STP_USE_DWARF_UNWINDER) && defined(STP_NEED_UNWIND_DATA)\n";
c->output << "static uint8_t _stp_module_" << stpmod_idx
<< "_eh_frame[] = \n";

15
systemtap.spec
View File

@ -9,7 +9,7 @@
Name: systemtap
Version: 1.0
Release: 1%{?dist}
Release: 2%{?dist}
# for version, see also configure.ac
Summary: Instrumentation System
Group: Development/System
@ -61,6 +61,11 @@ BuildRequires: xmlto /usr/share/xmlto/format/fo/pdf
BuildRequires: gtkmm24-devel >= 2.8
%endif
# Fix three --unprivileged DOS issues (CVE-2009-2911)
Patch10: SystemTap-1.0-limit-printf-arguments.patch
Patch11: SystemTap-1.0-limit-dwarf-expression-stack-size.patch
Patch12: SystemTap-1.0-unwind-table-size-checks.patch
%description
SystemTap is an instrumentation system for systems running Linux 2.6.
Developers can write instrumentation to collect data on the operation
@ -164,6 +169,11 @@ find . \( -name configure -o -name config.h.in \) -print | xargs touch
cd ..
%endif
# Fix three --unprivileged DOS issues (CVE-2009-2911)
%patch10 -p1
%patch11 -p1
%patch12 -p1
%build
%if %{with_bundled_elfutils}
@ -387,6 +397,9 @@ exit 0
%changelog
* Wed Oct 21 2009 Josh Stone <jistone@redhat.com> - 1.0-2
- Fix three --unprivileged DOS issues (CVE-2009-2911)
* Tue Sep 22 2009 Josh Stone <jistone@redhat.com> - 1.0-1
- Upstream release.