text stringlengths 0 1.99k |
|---|
h = { |
endp = 0x5a5a5a5a5a5a5a5a, |
next = 0x5a5a5a5a5a5a5a5a, |
first_avail = 0x5644f0439c91 |
} |
gef➤ |
Let's also put a breakpoint on pool.c:597 in case we lose the control of p, |
and continue the execution: |
gef➤ break pool.c:597 if (p && p->first >= 0x4141414141414141) |
gef➤ c |
Humm, interesting. It seems that it's allocating a buffer to store the |
responses to our commands. Let's recap the previous and the current |
answers: |
First break: |
────────────────────────────────────────────────────────────── trace ──── |
[#0] 0x5644eeabd5cd → alloc_pool(p=0x5644f0439bd1, reqsz=0x4, exact=0x0) |
[#1] 0x5644eeabd6b0 → palloc(p=0x5644f0439bd1, sz=0x4) |
[#2] 0x5644eeabf409 → pstrdup(p=0x5644f0439bd1, str=0x5644f0408dd0 "426") |
[#3] 0x5644eeaeb6f0 → pr_response_set_pool(p=0x5644f0439bd1) |
Second break (current): |
────────────────────────────────────────────────────────────── trace ──── |
[#0] 0x5644eeabd5a1 → alloc_pool(p=0x5644f0439c51, reqsz=0x29, exact=0x0) |
[#1] 0x5644eeabd6b0 → palloc(p=0x5644f0439c51, sz=0x29) |
[#2] 0x5644eeabf409 → pstrdup(p=0x5644f0439c51, str=0x5644f0408de0 |
"Transfer aborted. Data connection closed") |
[#3] 0x5644eeaeb721 → pr_response_set_pool(p=0x5644f0439c51) |
As we know, p points to resp_pool which was set in pr_response_set_pool(). |
ProFTPd uses the p->last block to store error messages due to lost data |
connections. |
At the first break it contained the "426" error code. At the second break |
the string "Transfer aborted. Data connection closed" is seen. We also know |
the size of each string from the reqsz parameter. |
We can continue with gdb two more times; it will print the "426" error code |
and the string again. |
On the 5th time we'll get SIGSEGV in another function: |
$rax : 0x4141414141414141 ("AAAAAAAA"?) |
$rbx : 0x000055555567aac0 → 0x0000000000000002 |
$rcx : 0x00005555556db030 → 0x0000000000000000 |
$rdx : 0x00005555556dae30 → 0x00005555556dae10 |
$rsp : 0x00007fffffffd940 → 0x0000000000000000 |
$rbp : 0x00007fffffffd960 → 0x00007fffffffda00 |
$rsi : 0x0 |
$rdi : 0x00005555556dae30 → 0x00005555556dae10 |
$rip : 0x00005555555757d5 → <make_sub_pool+197> |
$r8 : 0x56a |
$r9 : 0x0000555555674dc0 → 0x0000000000000001 |
$r10 : 0x00007ffff7eff040 → 0x0000000000000000 |
$r11 : 0x9 |
$r12 : 0x00007fffffffe3f8 → 0x00007fffffffe68d |
$r13 : 0x00005555555734ea → <main+0> endbr64 |
$r14 : 0x0 |
$r15 : 0x00007ffff7ffbc40 → 0x00050f0800000000 |
──────────────────────────────────────────────────────────────── stack ──── |
0x00007fffffffd940│+0x0000: 0x0000000000000000 ← $rsp |
0x00007fffffffd948│+0x0008: 0x0000555555712760 → "DDDDDDDDp'qUUU" |
0x00007fffffffd950│+0x0010: 0x00005555556dae10 → 0x00005555556db030 |
0x00007fffffffd958│+0x0018: 0x00005555556dae30 → 0x00005555556dae10 |
0x00007fffffffd960│+0x0020: 0x00007fffffffda00 → 0x00007fffffffda40 |
0x00007fffffffd968│+0x0028: 0x000055555556f7be → <_dispatch+577> |
0x00007fffffffd970│+0x0030: 0x00005555556d5da8 → 0x0000000000000000 |
0x00007fffffffd978│+0x0038: 0x000055555563d3b1 → 0x660000000000002a |
────────────────────────────────────────────────────────── code:x86:64 ──── |
0x5555555757c9 <make_sub_pool+185> mov rax, QWORD PTR [rbp-0x8] |
0x5555555757cd <make_sub_pool+189> mov rax, QWORD PTR [rax+0x20] |
0x5555555757d1 <make_sub_pool+193> mov rdx, QWORD PTR [rbp-0x8] |
→ 0x5555555757d5 <make_sub_pool+197> mov QWORD PTR [rax+0x28], rdx |
0x5555555757d9 <make_sub_pool+201> mov rax, QWORD PTR [rbp-0x18] |
0x5555555757dd <make_sub_pool+205> mov rdx, QWORD PTR [rbp-0x8] |
0x5555555757e1 <make_sub_pool+209> mov QWORD PTR [rax+0x18], rdx |
0x5555555757e5 <make_sub_pool+213> call <pr_alarms_unblock> |
0x5555555757ea <make_sub_pool+218> mov rax, QWORD PTR [rbp-0x8] |
──────────────────────────────────────────────────── source:pool.c+435 ──── |
430 if (p) { |
431 new_pool->parent = p; |
432 new_pool->sub_next = p->sub_pools; |
433 |
434 if (new_pool->sub_next) |
→ 435 new_pool->sub_next->sub_prev = new_pool; |
436 |
437 p->sub_pools = new_pool; |
438 } |
439 |
440 pr_alarms_unblock(); |
────────────────────────────────────────────────────────────── threads ──── |
[#0] Id 1, Name: "proftpd", stopped in make_sub_pool (), reason: SIGSEGV |
──────────────────────────────────────────────────────────────── trace ──── |
[#0] 0x5555555757d5 → make_sub_pool(p=0x555555712760) |
[#1] 0x55555556f7be → _dispatch(cmd=0x5555556d24f8, cmd_type=0x6, [...] |
[#2] 0x5555555708a6 → pr_cmd_dispatch_phase(cmd=0x5555556d24f8, [...] |
[#3] 0x5555555fc5f9 → xfer_exit_ev(event_data=0x0, user_data=0x0) |
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