From 75031b1f9ee0680875b4e28ae66b4d339186350f Mon Sep 17 00:00:00 2001 From: Fredrik Strupe Date: Mon, 5 Apr 2021 21:52:05 +0100 Subject: [PATCH] ARM: 9071/1: uprobes: Don't hook on thumb instructions commit d2f7eca60b29006285d57c7035539e33300e89e5 upstream. Since uprobes is not supported for thumb, check that the thumb bit is not set when matching the uprobes instruction hooks. The Arm UDF instructions used for uprobes triggering (UPROBE_SWBP_ARM_INSN and UPROBE_SS_ARM_INSN) coincidentally share the same encoding as a pair of unallocated 32-bit thumb instructions (not UDF) when the condition code is 0b1111 (0xf). This in effect makes it possible to trigger the uprobes functionality from thumb, and at that using two unallocated instructions which are not permanently undefined. Signed-off-by: Fredrik Strupe Cc: stable@vger.kernel.org Fixes: c7edc9e326d5 ("ARM: add uprobes support") Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman --- arch/arm/probes/uprobes/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm/probes/uprobes/core.c b/arch/arm/probes/uprobes/core.c index bf992264060e..b1b7b51c938c 100644 --- a/arch/arm/probes/uprobes/core.c +++ b/arch/arm/probes/uprobes/core.c @@ -207,7 +207,7 @@ unsigned long uprobe_get_swbp_addr(struct pt_regs *regs) static struct undef_hook uprobes_arm_break_hook = { .instr_mask = 0x0fffffff, .instr_val = (UPROBE_SWBP_ARM_INSN & 0x0fffffff), - .cpsr_mask = MODE_MASK, + .cpsr_mask = (PSR_T_BIT | MODE_MASK), .cpsr_val = USR_MODE, .fn = uprobe_trap_handler, }; @@ -215,7 +215,7 @@ static struct undef_hook uprobes_arm_break_hook = { static struct undef_hook uprobes_arm_ss_hook = { .instr_mask = 0x0fffffff, .instr_val = (UPROBE_SS_ARM_INSN & 0x0fffffff), - .cpsr_mask = MODE_MASK, + .cpsr_mask = (PSR_T_BIT | MODE_MASK), .cpsr_val = USR_MODE, .fn = uprobe_trap_handler, };