@@ -201,6 +201,21 @@ static inline int insn_offset_immediate(struct insn *insn)
return insn_offset_displacement(insn) + insn->displacement.nbytes;
}
+/**
+ * for_each_insn_prefix() -- Iterate prefixes in the instruction
+ * @insn: Pointer to struct insn.
+ * @idx: Index storage.
+ * @prefix: Prefix byte.
+ *
+ * Iterate prefix bytes of given @insn. Each prefix byte is stored in @prefix
+ * and the index is stored in @idx (note that this @idx is just for a cursor,
+ * do not change it.)
+ * Since prefixes.nbytes can be bigger than 4 if some prefixes
+ * are repeated, it cannot be used for looping over the prefixes.
+ */
+#define for_each_insn_prefix(insn, idx, prefix) \
+ for (idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++)
+
#define POP_SS_OPCODE 0x1f
#define MOV_SREG_OPCODE 0x8e
@@ -255,12 +255,13 @@ static volatile u32 good_2byte_insns[256 / 32] = {
static bool is_prefix_bad(struct insn *insn)
{
+ insn_byte_t p;
int i;
- for (i = 0; i < insn->prefixes.nbytes; i++) {
+ for_each_insn_prefix(insn, i, p) {
insn_attr_t attr;
- attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]);
+ attr = inat_get_opcode_attribute(p);
switch (attr) {
case INAT_MAKE_PREFIX(INAT_PFX_ES):
case INAT_MAKE_PREFIX(INAT_PFX_CS):
@@ -715,6 +716,7 @@ static const struct uprobe_xol_ops push_xol_ops = {
static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
{
u8 opc1 = OPCODE1(insn);
+ insn_byte_t p;
int i;
switch (opc1) {
@@ -746,8 +748,8 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
* Intel and AMD behavior differ in 64-bit mode: Intel ignores 66 prefix.
* No one uses these insns, reject any branch insns with such prefix.
*/
- for (i = 0; i < insn->prefixes.nbytes; i++) {
- if (insn->prefixes.bytes[i] == 0x66)
+ for_each_insn_prefix(insn, i, p) {
+ if (p == 0x66)
return -ENOTSUPP;
}
@@ -201,6 +201,21 @@ static inline int insn_offset_immediate(struct insn *insn)
return insn_offset_displacement(insn) + insn->displacement.nbytes;
}
+/**
+ * for_each_insn_prefix() -- Iterate prefixes in the instruction
+ * @insn: Pointer to struct insn.
+ * @idx: Index storage.
+ * @prefix: Prefix byte.
+ *
+ * Iterate prefix bytes of given @insn. Each prefix byte is stored in @prefix
+ * and the index is stored in @idx (note that this @idx is just for a cursor,
+ * do not change it.)
+ * Since prefixes.nbytes can be bigger than 4 if some prefixes
+ * are repeated, it cannot be used for looping over the prefixes.
+ */
+#define for_each_insn_prefix(insn, idx, prefix) \
+ for (idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++)
+
#define POP_SS_OPCODE 0x1f
#define MOV_SREG_OPCODE 0x8e
The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 4e9a5ae8df5b3365183150f6df49e49dece80d8c Gitweb: https://git.kernel.org/tip/4e9a5ae8df5b3365183150f6df49e49dece80d8c Author: Masami Hiramatsu <mhiramat@kernel.org> AuthorDate: Thu, 03 Dec 2020 13:50:37 +09:00 Committer: Borislav Petkov <bp@suse.de> CommitterDate: Sun, 06 Dec 2020 09:58:13 +01:00 x86/uprobes: Do not use prefixes.nbytes when looping over prefixes.bytes Since insn.prefixes.nbytes can be bigger than the size of insn.prefixes.bytes[] when a prefix is repeated, the proper check must be insn.prefixes.bytes[i] != 0 and i < 4 instead of using insn.prefixes.nbytes. Introduce a for_each_insn_prefix() macro for this purpose. Debugged by Kees Cook <keescook@chromium.org>. [ bp: Massage commit message, sync with the respective header in tools/ and drop "we". ] Fixes: 2b1444983508 ("uprobes, mm, x86: Add the ability to install and remove uprobes breakpoints") Reported-by: syzbot+9b64b619f10f19d19a7c@syzkaller.appspotmail.com Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/160697103739.3146288.7437620795200799020.stgit@devnote2 --- arch/x86/include/asm/insn.h | 15 +++++++++++++++ arch/x86/kernel/uprobes.c | 10 ++++++---- tools/arch/x86/include/asm/insn.h | 15 +++++++++++++++ 3 files changed, 36 insertions(+), 4 deletions(-)