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Description of problem:
Concurrent DELETE and PROPFIND breaks PROPFIND.
When executing DELETE and PROPFIND at the same time, PROPFIND may return an empty response.
Version-Release number of selected component (if applicable):
httpd-2.4.53-11.el9_2.5.x86_64
How reproducible:
Steps to Reproduce:
1. provide a container and install httpd:
$ sudo subscription-manager register --force --username <red hat customer portal account name>
$ podman rm -f rhel9test
$ podman login registry.redhat.io
$ podman run -it --privileged --cap-add=SYS_PTRACE --name rhel9test registry.redhat.io/ubi9/ubi
# dnf install -y --enablerepo rhel-9-for-x86_64-appstream-rpms gdb httpd iproute procps-ng vim
# dnf debuginfo-install -y glibc httpd
2. create config files:
# vim /etc/httpd/conf.d/dav.conf
DavLockDB /var/www/davlock/db
Alias /dav /var/www/dav
<Directory /var/www/dav>
LogLevel trace8
Dav On
DirectoryIndex disabled
</Directory>
# vim /etc/httpd/conf.d/mpm.conf
ServerLimit 4
StartServers 1
MinSpareThreads 1
MaxSpareThreads 4
ThreadsPerChild 4
MaxRequestWorkers 1000
3. create dav contents:
# mkdir /var/www/dav
# mkdir /var/www/davlock
# chmod 777 /var/www/dav /var/www/davlock
# for i in x y z; do touch /var/www/dav/$i; chown apache:apache /var/www/dav/$i; done
4. start httpd:
# nohup /usr/sbin/httpd -DFOREGROUND &
5. attach gdb:
# ps -ef | grep httpd
# gdb -p <largest PID of httpd processes>
6. set break points:
(gdb) b unlink
(gdb) b lstat
7. run PROPFIND on another shell:
$ podman exec -it rhel9test /bin/bash
curl "http://localhost/dav/" -X PROPFIND -i -H 'Depth:1' -d '<?xml version="1.0" encoding="utf-8"?><D:propfind xmlns:D="DAV:"><D:allprop/></D:propfind>'
8. run DELETE on another shell:
$ podman exec -it rhel9test /bin/bash
curl -v "http://localhost/dav/z" -X DELETE
9. enter 'c' to gdb prompt several times:
(gdb) c
(gdb) c
(gdb) c
(gdb) c
(gdb) c
(gdb) c
(gdb) c
(gdb) c
(gdb) c
Then, you can observe the empty response and the error message in error_log:
# curl "http://localhost/dav/" -X PROPFIND -i -H 'Depth:1' -d '<?xml version="1.0" encoding="utf-8"?><D:propfind xmlns:D="DAV:"><D:allprop/></D:propfind>'
curl: (52) Empty reply from server
error_log:
[Wed Jun 07 08:04:32.922724 2023] [dav:error] [pid 354:tid 380] [client ::1:46944] Provider encountered an error while streaming a multistatus PROPFIND response. [404, #0]
Actual results:
Expected results:
Additional info:
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (Moderate: httpd and mod_http2 security, bug fix, and enhancement update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHSA-2023:6403
Description of problem: Concurrent DELETE and PROPFIND breaks PROPFIND. When executing DELETE and PROPFIND at the same time, PROPFIND may return an empty response. Version-Release number of selected component (if applicable): httpd-2.4.53-11.el9_2.5.x86_64 How reproducible: Steps to Reproduce: 1. provide a container and install httpd: $ sudo subscription-manager register --force --username <red hat customer portal account name> $ podman rm -f rhel9test $ podman login registry.redhat.io $ podman run -it --privileged --cap-add=SYS_PTRACE --name rhel9test registry.redhat.io/ubi9/ubi # dnf install -y --enablerepo rhel-9-for-x86_64-appstream-rpms gdb httpd iproute procps-ng vim # dnf debuginfo-install -y glibc httpd 2. create config files: # vim /etc/httpd/conf.d/dav.conf DavLockDB /var/www/davlock/db Alias /dav /var/www/dav <Directory /var/www/dav> LogLevel trace8 Dav On DirectoryIndex disabled </Directory> # vim /etc/httpd/conf.d/mpm.conf ServerLimit 4 StartServers 1 MinSpareThreads 1 MaxSpareThreads 4 ThreadsPerChild 4 MaxRequestWorkers 1000 3. create dav contents: # mkdir /var/www/dav # mkdir /var/www/davlock # chmod 777 /var/www/dav /var/www/davlock # for i in x y z; do touch /var/www/dav/$i; chown apache:apache /var/www/dav/$i; done 4. start httpd: # nohup /usr/sbin/httpd -DFOREGROUND & 5. attach gdb: # ps -ef | grep httpd # gdb -p <largest PID of httpd processes> 6. set break points: (gdb) b unlink (gdb) b lstat 7. run PROPFIND on another shell: $ podman exec -it rhel9test /bin/bash curl "http://localhost/dav/" -X PROPFIND -i -H 'Depth:1' -d '<?xml version="1.0" encoding="utf-8"?><D:propfind xmlns:D="DAV:"><D:allprop/></D:propfind>' 8. run DELETE on another shell: $ podman exec -it rhel9test /bin/bash curl -v "http://localhost/dav/z" -X DELETE 9. enter 'c' to gdb prompt several times: (gdb) c (gdb) c (gdb) c (gdb) c (gdb) c (gdb) c (gdb) c (gdb) c (gdb) c Then, you can observe the empty response and the error message in error_log: # curl "http://localhost/dav/" -X PROPFIND -i -H 'Depth:1' -d '<?xml version="1.0" encoding="utf-8"?><D:propfind xmlns:D="DAV:"><D:allprop/></D:propfind>' curl: (52) Empty reply from server error_log: [Wed Jun 07 08:04:32.922724 2023] [dav:error] [pid 354:tid 380] [client ::1:46944] Provider encountered an error while streaming a multistatus PROPFIND response. [404, #0] Actual results: Expected results: Additional info: