openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 170 insertions, 0 deletions

diff --git a/tools/perf/util/disasm.h b/tools/perf/util/disasm.h
new file mode 100644
index 000000000..25756e3f4
--- /dev/null
+++ b/tools/perf/util/disasm.h
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef __PERF_UTIL_DISASM_H
+#define __PERF_UTIL_DISASM_H
+
+#include "map_symbol.h"
+
+#ifdef HAVE_LIBDW_SUPPORT
+#include "dwarf-aux.h"
+#endif
+
+struct annotation_options;
+struct disasm_line;
+struct ins;
+struct evsel;
+struct symbol;
+struct data_loc_info;
+struct type_state;
+struct disasm_line;
+
+struct e_machine_and_e_flags {
+	uint32_t e_flags;
+	uint16_t e_machine;
+};
+
+struct arch {
+	/** @name: name such as "x86" or "powerpc". */
+	const char		*name;
+	const struct ins	*instructions;
+	size_t			nr_instructions;
+	size_t			nr_instructions_allocated;
+	const char		*insn_suffix;
+	unsigned int		model;
+	unsigned int		family;
+	/** @id: ELF machine and flags associated with arch. */
+	struct e_machine_and_e_flags id;
+	bool			sorted_instructions;
+	struct		{
+		char comment_char;
+		char skip_functions_char;
+		char register_char;
+		char memory_ref_char;
+		char imm_char;
+	} objdump;
+	bool		(*ins_is_fused)(const struct arch *arch, const char *ins1,
+					const char *ins2);
+	const struct ins_ops  *(*associate_instruction_ops)(struct arch *arch, const char *name);
+#ifdef HAVE_LIBDW_SUPPORT
+	void		(*update_insn_state)(struct type_state *state,
+				struct data_loc_info *dloc, Dwarf_Die *cu_die,
+				struct disasm_line *dl);
+#endif
+};
+
+struct ins {
+	const char     *name;
+	const struct ins_ops *ops;
+};
+
+struct ins_operands {
+	char	*raw;
+	struct {
+		char	*raw;
+		char	*name;
+		struct symbol *sym;
+		u64	addr;
+		s64	offset;
+		bool	offset_avail;
+		bool	outside;
+		bool	multi_regs;
+		bool	mem_ref;
+	} target;
+	union {
+		struct {
+			char	*raw;
+			char	*name;
+			u64	addr;
+			bool	multi_regs;
+			bool	mem_ref;
+		} source;
+		struct {
+			struct ins	    ins;
+			struct ins_operands *ops;
+		} locked;
+		struct {
+			char	*raw_comment;
+			char	*raw_func_start;
+		} jump;
+	};
+};
+
+struct ins_ops {
+	void (*free)(struct ins_operands *ops);
+	int (*parse)(const struct arch *arch, struct ins_operands *ops, struct map_symbol *ms,
+			struct disasm_line *dl);
+	int (*scnprintf)(const struct ins *ins, char *bf, size_t size,
+			 struct ins_operands *ops, int max_ins_name);
+	bool is_jump;
+	bool is_call;
+};
+
+struct annotate_args {
+	const struct arch	  *arch;
+	struct map_symbol	  *ms;
+	struct annotation_options *options;
+	s64			  offset;
+	char			  *line;
+	int			  line_nr;
+	char			  *fileloc;
+};
+
+const struct arch *arch__find(uint16_t e_machine, uint32_t e_flags, const char *cpuid);
+bool arch__is_x86(const struct arch *arch);
+bool arch__is_powerpc(const struct arch *arch);
+
+extern const struct ins_ops call_ops;
+extern const struct ins_ops dec_ops;
+extern const struct ins_ops jump_ops;
+extern const struct ins_ops mov_ops;
+extern const struct ins_ops nop_ops;
+extern const struct ins_ops lock_ops;
+extern const struct ins_ops ret_ops;
+
+int arch__associate_ins_ops(struct arch *arch, const char *name, const struct ins_ops *ops);
+
+const struct arch *arch__new_arc(const struct e_machine_and_e_flags *id, const char *cpuid);
+const struct arch *arch__new_arm(const struct e_machine_and_e_flags *id, const char *cpuid);
+const struct arch *arch__new_arm64(const struct e_machine_and_e_flags *id, const char *cpuid);
+const struct arch *arch__new_csky(const struct e_machine_and_e_flags *id, const char *cpuid);
+const struct arch *arch__new_loongarch(const struct e_machine_and_e_flags *id, const char *cpuid);
+const struct arch *arch__new_mips(const struct e_machine_and_e_flags *id, const char *cpuid);
+const struct arch *arch__new_powerpc(const struct e_machine_and_e_flags *id, const char *cpuid);
+const struct arch *arch__new_riscv64(const struct e_machine_and_e_flags *id, const char *cpuid);
+const struct arch *arch__new_s390(const struct e_machine_and_e_flags *id, const char *cpuid);
+const struct arch *arch__new_sparc(const struct e_machine_and_e_flags *id, const char *cpuid);
+const struct arch *arch__new_x86(const struct e_machine_and_e_flags *id, const char *cpuid);
+
+const struct ins_ops *ins__find(const struct arch *arch, const char *name, struct disasm_line *dl);
+
+bool ins__is_call(const struct ins *ins);
+bool ins__is_jump(const struct ins *ins);
+bool ins__is_fused(const struct arch *arch, const char *ins1, const char *ins2);
+bool ins__is_ret(const struct ins *ins);
+bool ins__is_lock(const struct ins *ins);
+
+const struct ins_ops *check_ppc_insn(struct disasm_line *dl);
+
+struct disasm_line *disasm_line__new(struct annotate_args *args);
+void disasm_line__free(struct disasm_line *dl);
+
+int disasm_line__scnprintf(struct disasm_line *dl, char *bf, size_t size,
+			   bool raw, int max_ins_name);
+
+int ins__raw_scnprintf(const struct ins *ins, char *bf, size_t size,
+			   struct ins_operands *ops, int max_ins_name);
+int ins__scnprintf(const struct ins *ins, char *bf, size_t size,
+		   struct ins_operands *ops, int max_ins_name);
+int call__scnprintf(const struct ins *ins, char *bf, size_t size,
+		    struct ins_operands *ops, int max_ins_name);
+int jump__scnprintf(const struct ins *ins, char *bf, size_t size,
+		    struct ins_operands *ops, int max_ins_name);
+int mov__scnprintf(const struct ins *ins, char *bf, size_t size,
+		   struct ins_operands *ops, int max_ins_name);
+
+void jump__delete(struct ins_operands *ops);
+
+int symbol__disassemble(struct symbol *sym, struct annotate_args *args);
+
+char *expand_tabs(char *line, char **storage, size_t *storage_len);
+
+#endif /* __PERF_UTIL_DISASM_H */