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fix(esp_system): prevent .eh_frame-based unwinding from looping indefinitely

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This commit is contained in:
Omar Chebib
2025-08-11 16:21:20 +08:00
parent 01d0a2c14f
commit 3fa48d628a
1 changed files with 25 additions and 6 deletions
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components/esp_system/eh_frame_parser.c
+25 -6
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@@ -28,6 +28,8 @@
#error "Unsupported architecture for unwinding"
#endif
#define MAX_ITERATIONS 100
/**
* @brief Dimension of an array (number of elements)
*/
@@ -589,7 +591,8 @@ static inline uint32_t esp_eh_frame_execute_opcode_0(const uint32_t opcode, cons
* @param state DWARF machine state. The registers contained in the state will
* modified accordingly to the instructions.
*
* @return true if the execution went fine, false if an unsupported instruction was met.
* @return true if the execution went fine, false if an unsupported instruction was met or if the DWARF
* instructions were not enough (not properly generated) to reach the current location (PC).
*/
static bool esp_eh_frame_execute(const uint8_t* instructions, const uint32_t instructions_length,
const ExecutionFrame* frame, dwarf_regs* state)
@@ -637,8 +640,18 @@ static bool esp_eh_frame_execute(const uint8_t* instructions, const uint32_t ins
/* As the state->location can also be modified by 0-opcode instructions (in the function)
* and also because we need to break the loop (and not only the switch), let's put this
* check here, after the execution of the instruction, outside of the switch block. */
if (state->location >= EXECUTION_FRAME_PC(*frame)) {
* check here, after the execution of the instruction, outside of the switch block.
* We should stop executing the opcodes as soon as we go AFTER the program counter that
* interests us. For example, if we have the following DWARF instructions:
* ```
* DW_CFA_advance_loc: 2 to 40382ecc
* DW_CFA_offset: r1 (ra) at cfa-4
* DW_CFA_nop
* ```
* And out current PC is `0x40382ecc`, we MUST execute the instructions that are after it
* (until the next DW_CFA_advance_loc, where we would need to stop)
* */
if (state->location > EXECUTION_FRAME_PC(*frame)) {
break;
}
}
@@ -866,7 +879,7 @@ void esp_eh_frame_print_backtrace(const void *frame_or)
ExecutionFrame frame = *((ExecutionFrame*) frame_or);
uint32_t size = 0;
uint8_t* enc_values = NULL;
bool end_of_backtrace = false;
int iterations = 0;
/* Start parsing the .eh_frame_hdr section. */
fde_header* header = (fde_header*) EH_FRAME_HDR_ADDR;
@@ -893,7 +906,7 @@ void esp_eh_frame_print_backtrace(const void *frame_or)
const table_entry* sorted_table = (const table_entry*) enc_values;
panic_print_str("Backtrace:");
while (!end_of_backtrace) {
for (iterations = 1; iterations < MAX_ITERATIONS; iterations++) {
/* Output one step of the backtrace. */
esp_eh_frame_generated_step(EXECUTION_FRAME_PC(frame), EXECUTION_FRAME_SP(frame));
@@ -927,13 +940,19 @@ void esp_eh_frame_print_backtrace(const void *frame_or)
uint32_t ra = esp_eh_frame_restore_caller_state(fde, &frame, &state);
/* End of backtrace is reached if the stack and the PC don't change anymore. */
end_of_backtrace = (EXECUTION_FRAME_SP(frame) == prev_sp) && (EXECUTION_FRAME_PC(frame) == ra);
if ((EXECUTION_FRAME_SP(frame) == prev_sp) && (EXECUTION_FRAME_PC(frame) == ra)) {
break;
}
/* Go back to the caller: update stack pointer and program counter. */
EXECUTION_FRAME_PC(frame) = ra;
}
panic_print_str("\r\n");
if (iterations >= MAX_ITERATIONS) {
panic_print_str("Backtrace ended abruptly: maximum iterations reached\r\n");
}
}
/**