mainline: 29eb51101c02df517ca64ec472d7501127ad1da8
-- Thanks, Oliver
--- Begin Message ---Handle bogus %cs selector in single-step instruction decoding The code for LDT segment selectors was not robust in the face of a bogus selector set in %cs via ptrace before the single-step was done. Signed-off-by: Roland McGrath <[EMAIL PROTECTED]> Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]> Acked-by: Jeff Mahoney <[EMAIL PROTECTED]> --- arch/i386/kernel/ptrace.c | 22 +++++++++++++++------- arch/x86_64/kernel/ptrace.c | 23 ++++++++++++++++------- 2 files changed, 31 insertions(+), 14 deletions(-) diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c index 1c075f5..0c8f00e 100644 --- a/arch/i386/kernel/ptrace.c +++ b/arch/i386/kernel/ptrace.c @@ -164,14 +164,22 @@ static unsigned long convert_eip_to_linear(struct task_struct *child, struct pt_ u32 *desc; unsigned long base; - down(&child->mm->context.sem); - desc = child->mm->context.ldt + (seg & ~7); - base = (desc[0] >> 16) | ((desc[1] & 0xff) << 16) | (desc[1] & 0xff000000); + seg &= ~7UL; - /* 16-bit code segment? */ - if (!((desc[1] >> 22) & 1)) - addr &= 0xffff; - addr += base; + down(&child->mm->context.sem); + if (unlikely((seg >> 3) >= child->mm->context.size)) + addr = -1L; /* bogus selector, access would fault */ + else { + desc = child->mm->context.ldt + seg; + base = ((desc[0] >> 16) | + ((desc[1] & 0xff) << 16) | + (desc[1] & 0xff000000)); + + /* 16-bit code segment? */ + if (!((desc[1] >> 22) & 1)) + addr &= 0xffff; + addr += base; + } up(&child->mm->context.sem); } return addr; diff --git a/arch/x86_64/kernel/ptrace.c b/arch/x86_64/kernel/ptrace.c index fa6775e..e83cc67 100644 --- a/arch/x86_64/kernel/ptrace.c +++ b/arch/x86_64/kernel/ptrace.c @@ -102,16 +102,25 @@ unsigned long convert_rip_to_linear(struct task_struct *child, struct pt_regs *r u32 *desc; unsigned long base; - down(&child->mm->context.sem); - desc = child->mm->context.ldt + (seg & ~7); - base = (desc[0] >> 16) | ((desc[1] & 0xff) << 16) | (desc[1] & 0xff000000); + seg &= ~7UL; - /* 16-bit code segment? */ - if (!((desc[1] >> 22) & 1)) - addr &= 0xffff; - addr += base; + down(&child->mm->context.sem); + if (unlikely((seg >> 3) >= child->mm->context.size)) + addr = -1L; /* bogus selector, access would fault */ + else { + desc = child->mm->context.ldt + seg; + base = ((desc[0] >> 16) | + ((desc[1] & 0xff) << 16) | + (desc[1] & 0xff000000)); + + /* 16-bit code segment? */ + if (!((desc[1] >> 22) & 1)) + addr &= 0xffff; + addr += base; + } up(&child->mm->context.sem); } + return addr; }
--- End Message ---
