Lab 3 - IDA

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<strong>Lab</strong> 3: Example: bad stack pointer • A user program controls its own stackpointer: asm volatile ( ”movl $0x0, %esp; int $0x30” ::: ); • What will happen in kernel? • syscall_handler will look at the stack to find out which syscall it is: syscall_handler(...) { ... switch (*esp) // *(0) • The kernel will crash if you don't check esp. 28
Bad string argument • User program: create((char*)NULL, 17); • syscall_handler will call: filesys_create( (char*)arg0, arg1); • But, arg0 is NULL – filesys_create will crash the kernel • You must: – First check stack pointer – Then check the pointer that is on the stack – Check all pages until you read '\0' 29
Page 1 and 2: TDDB68 2011 Lesson 2 Pintos Assignm
Page 3 and 4: Instead of Motivation • Some of y
Page 5 and 6: Lab 3: overview • Part A - Multip
Page 7 and 8: Exec & wait example: src/examples/s
Page 9 and 10: Part A Lab 3: Exec • pid_t exec (
Page 11 and 12: Lab 3: Exec Starting the child Pare
Page 13 and 14: Lab 3: Situations with Wait • Chi
Page 15 and 16: Lab 3: Situations with Wait • Chi
Page 17 and 18: Reference counting “poor man's ga
Page 19 and 20: Lab 3: Part B • Sometimes we want
Page 21 and 22: Lab 3: Part B • Every time you do
Page 23 and 24: Lab 3 (B): Program arguments • ST
Page 25 and 26: Address Name Data Type 0xbffffffd a
Page 27: Lab 3 : Part C • Part C: Making t
Page 31 and 32: Lab 3 : Pointer paranoia Memory val
Page 33 and 34: Lab 4: General Description • Lab
Page 35 and 36: Lab 4: Files (2) • devices/disk.[
Page 37 and 38: Lab 4: Additional System Calls •
Page 39 and 40: Lab 4: Final Tests • For testing

Lab 3 - IDA

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