Frequent SIGPIPEs with iOS 17.4

[abustany]

On a large-ish webpage with iOS 17.4 and the latest release of IWDP, I get a crash due to a SIGPIPE almost instantly:

#0  0x00007ffff7836904 in write () from /nix/store/7jiqcrg061xi5clniy7z5pvkc4jiaqav-glibc-2.38-27/lib/libc.so.6
#1  0x00007ffff7b07a8b in sock_write () from /nix/store/1l3a02nqq5b5v7rhchj89hi7plmbza5r-openssl-3.0.12/lib/libcrypto.so.3
#2  0x00007ffff7afe117 in bwrite_conv () from /nix/store/1l3a02nqq5b5v7rhchj89hi7plmbza5r-openssl-3.0.12/lib/libcrypto.so.3
#3  0x00007ffff7afca6c in BIO_write () from /nix/store/1l3a02nqq5b5v7rhchj89hi7plmbza5r-openssl-3.0.12/lib/libcrypto.so.3
#4  0x00007ffff7ef5dd9 in ssl3_write_pending () from /nix/store/1l3a02nqq5b5v7rhchj89hi7plmbza5r-openssl-3.0.12/lib/libssl.so.3
#5  0x00007ffff7ef6e32 in do_ssl3_write[localalias] () from /nix/store/1l3a02nqq5b5v7rhchj89hi7plmbza5r-openssl-3.0.12/lib/libssl.so.3
#6  0x00007ffff7ecbd8a in ssl3_dispatch_alert () from /nix/store/1l3a02nqq5b5v7rhchj89hi7plmbza5r-openssl-3.0.12/lib/libssl.so.3
#7  0x00007ffff7f09cf5 in ossl_statem_fatal () from /nix/store/1l3a02nqq5b5v7rhchj89hi7plmbza5r-openssl-3.0.12/lib/libssl.so.3
#8  0x00007ffff7ef5c86 in ssl3_read_n () from /nix/store/1l3a02nqq5b5v7rhchj89hi7plmbza5r-openssl-3.0.12/lib/libssl.so.3
#9  0x00007ffff7ef96f4 in ssl3_get_record () from /nix/store/1l3a02nqq5b5v7rhchj89hi7plmbza5r-openssl-3.0.12/lib/libssl.so.3
#10 0x00007ffff7ef8220 in ssl3_read_bytes () from /nix/store/1l3a02nqq5b5v7rhchj89hi7plmbza5r-openssl-3.0.12/lib/libssl.so.3
#11 0x00007ffff7eca9e9 in ssl3_read () from /nix/store/1l3a02nqq5b5v7rhchj89hi7plmbza5r-openssl-3.0.12/lib/libssl.so.3
#12 0x00007ffff7ed71a3 in SSL_read () from /nix/store/1l3a02nqq5b5v7rhchj89hi7plmbza5r-openssl-3.0.12/lib/libssl.so.3
#13 0x000000000040dafc in sm_recv (self=self@entry=0x423900, fd=fd@entry=7) at socket_manager.c:599
#14 0x000000000040e725 in sm_select (self=0x423900, timeout_secs=<optimized out>) at socket_manager.c:677
#15 0x0000000000403fb4 in main (argc=<optimized out>, argv=<optimized out>) at ios_webkit_debug_proxy_main.c:96

I used the following gdb command to "mask" the SIGPIPES:

handle SIGPIPE nostop nopass

and IWDP works fine 🤷 I have no idea what's causing those SIGPIPEs... Would a dummy SIGPIPE handler would make sense? Since the code handles the error codes from OpenSSL already.

[abustany]

hmm actually it seems the signal mask hack is not 100% working, I do still get ssl recv failed: Broken pipe and a disconnection from time to time.

[artygus]

hey @abustany, I wasn't able to repro it (openssl 3.1 + ios 17.4.1). any chance you could share a website url?

[foodornt]

Hey where did you ran handle SIGPIPE nostop nopass to make it work? ChatGPT told me it's gnu debugger but that's gonna be big effort to learn that

If somebody can give me few commands to run ios debug proxy in gdb i'd REALLY appreciate it 🙌❤️

[abustany]

Just run the program prexifing the command with gdb —args , type in the handle commands and start the program with run :)

@artygus sorry for not replying earlier, I switched to some other task and somehow that slipped through the cracks… The error wasn’t linked to a page in particular, it was happening everywhere. I’m mostly using browserstack now to debug on iOS devices so I haven’t used this project much lately.

[artygus]

@abustany no problem at all! thank for coming back to me.

I have mixed feelings about using dummy handler for SIGPIPE, it may hide the real problem, however it seems to be a common approach in the libimobiledevice tools set https://github.com/search?q=repo%3Alibimobiledevice%2Flibimobiledevice+sigpipe&type=code 🤔

[abustany]

My (limited) understanding is that SIGPIPE doesn't really bring any value as a signal, since we already get an error from the write calls (or in this case, from OpenSSL calling write). I wonder if this issue is linked to openssl/openssl#16399 ?

[abustany]

Thanks :)