https://bugs.exim.org/show_bug.cgi?id=2215
Bug ID: 2215
Summary: SIGSEGV in dns_basic_lookup()
Product: Exim
Version: 4.90
Hardware: x86
OS: Linux
Status: NEW
Severity: bug
Priority: medium
Component: Lookups
Assignee: nigel@???
Reporter: wbreyha@???
CC: exim-dev@???
After I deployed 4.90 to all my hosts two of them started to segfault heavily.
Checking the others I recognized that same of them occasionally segfaulted as
well. At this point I roled back to 4.89 before xmas.
Now I put 4.90 back on two hosts and after I activated coredumps I promptly got
some again and they all have frames #0-#2 in common:
#0 0x0000003ed2d2868a in __strcmp_sse42 () from /lib64/libc.so.6
#1 0x00000000004b22c3 in tree_search (p=0xa20656e6f6e,
name=0x7ffd5675f000 "_adsp._domainkey.newsletter-hub.com-TXT-80041") at
tree.c:335
#2 0x000000000043ce74 in dns_basic_lookup (dnsa=0x7ffd567628b0, name=0x1a4b960
"_adsp._domainkey.newsletter-hub.com",
type=16) at dns.c:668
dns_basic_lookup()->tree_search()->strcmp()
In fact the tree "tree_dns_fails" used in
(gdb) frame 2
#2 0x000000000043ce74 in dns_basic_lookup (dnsa=0x7ffd567628b0, name=0x1a4b960
"_adsp._domainkey.newsletter-hub.com",
type=16) at dns.c:668
668 if ((previous = tree_search(tree_dns_fails, node_name)))
has an invalid entry:
(gdb) print *tree_dns_fails
$2 = {left = 0x1a16628, right = 0x1a16478, data = {ptr = 0x2, val = 2}, balance
= 0 '\000', name = "m"}
(gdb) print *(tree_dns_fails->right)
$3 = {left = 0x0, right = 0x1a15ed8, data = {ptr = 0x2, val = 2}, balance = 2
'\002', name = "p"}
(gdb) print *(tree_dns_fails->right->right)
$4 = {left = 0x0, right = 0x0, data = {ptr = 0x2, val = 2}, balance = 0 '\000',
name = "s"}
(gdb) print *(tree_dns_fails->left)
$5 = {left = 0x1a167d8, right = 0x1a76188, data = {ptr = 0x1, val = 1}, balance
= 0 '\000', name = "1"}
(gdb) print *(tree_dns_fails->left->right)
$6 = {left = 0xa20656e6f6e, right = 0x656976696e552d58, data = {ptr =
0x68432d4d494b442d, val = 1229669421},
balance = 101 'e', name = "c"}
(gdb) print *(tree_dns_fails->left->left)
$7 = {left = 0x0, right = 0x0, data = {ptr = 0x1, val = 1}, balance = 0 '\000',
name = "1"}
note $6 which left and right pointers are invalid, but used later in tree
search
(gdb) frame 1
#1 0x00000000004b22c3 in tree_search (p=0xa20656e6f6e,
name=0x7ffd5675f000 "_adsp._domainkey.newsletter-hub.com-TXT-80041") at
tree.c:335
335 int c = Ustrcmp(name, p->name);
(gdb) print p
$8 = (tree_node *) 0xa20656e6f6e
I've not found the reason why this happens mostly on two of my hosts yet. They
are the last hosts where I do the legacy _adsp.... lookups. Maybe this triggers
problems with tree_dns_fails best, because of many failed lookups?
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