Bug#481543: libc6: low-memory snprintf provokes internal segfault
This demonstrates that it is indeed a.out/libc that provokes
the segfault. Here's the output I get:
[2331489.137491] zsh[21289]: segfault at 0 ip 7f1126c824f4 sp \
7fff2fa49778 error 6 in libc-2.7.so[7f1126c06000+14a000]
Do the same thing with true, and there's no problem:
$ env -u -- zsh -f -c 'ulimit -v 5000; /bin/true' || dmesg|tail -1
But if you use a command that calls printf or other stream output
functions, it'll fail because glibc's stream output initialization code
tries to allocate space and fails, and then segfaults.
For me, it does not segfault, the mmap fails, the snprintf() returns -1
and the program regularly ends.
mmap(NULL, 5246976, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = -1 ENOMEM (Cannot allocate memory)
brk(0xbae000) = 0x6ad000
mmap(NULL, 5378048, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = -1 ENOMEM (Cannot allocate memory)
mmap(NULL, 134217728, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = -1 ENOMEM (Cannot allocate memory)
mmap(NULL, 67108864, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = -1 ENOMEM (Cannot allocate memory)
mmap(NULL, 134217728, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = -1 ENOMEM (Cannot allocate memory)
mmap(NULL, 67108864, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = -1 ENOMEM (Cannot allocate memory)
exit_group(0) = ?
The gcc is 4.3.2-2, libc6 is 2.7-15.
Petr
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