Em Sat, Dec 05, 2020 at 09:12:56AM +0900, Masami Hiramatsu escreveu:
On Fri, 04 Dec 2020 15:04:03 -0000 "tip-bot2 for Masami Hiramatsu" tip-bot2@linutronix.de wrote:
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: 9dc23f960adb9ce410ef835b32a2398fdb09c828 Gitweb: https://git.kernel.org/tip/9dc23f960adb9ce410ef835b32a2398fdb09c828 Author: Masami Hiramatsu mhiramat@kernel.org AuthorDate: Thu, 03 Dec 2020 13:50:37 +09:00 Committer: Borislav Petkov bp@suse.de CommitterDate: Fri, 04 Dec 2020 14:32:57 +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@dev...
arch/x86/include/asm/insn.h | 15 +++++++++++++++ arch/x86/kernel/uprobes.c | 10 ++++++---- tools/arch/x86/include/asm/insn.h | 17 ++++++++++++++++- 3 files changed, 37 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/insn.h b/arch/x86/include/asm/insn.h index 5c1ae3e..a8c3d28 100644 --- a/arch/x86/include/asm/insn.h +++ b/arch/x86/include/asm/insn.h @@ -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 diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 3fdaa04..138bdb1 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -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);@@ -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;diff --git a/tools/arch/x86/include/asm/insn.h b/tools/arch/x86/include/asm/insn.h index 568854b..a8c3d28 100644 --- a/tools/arch/x86/include/asm/insn.h +++ b/tools/arch/x86/include/asm/insn.h @@ -8,7 +8,7 @@ */ /* insn_attr_t is defined in inat.h */ -#include "inat.h" +#include <asm/inat.h>
This may break tools/objtool build. Please keep "inat.h".
And also it would be interesting to avoid updating both the kernel and the tools/ copy, otherwise one would have to test the tools build, which may break with such updates.
The whole point of the copy is to avoid that, otherwise we could just use the kernel files directly.
- Arnaldo