Tested and fails also on m68k Linux 4.16 -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1994079
Title: fallocate on 32 bit boundary on 32 bit systems with setrlimit fails to generate SIGXFSZ signal Status in Linux: Confirmed Status in linux package in Ubuntu: New Bug description: This is a corner case on 32 bit systems when using large file offsets, fallocate and setrlimit. Setting the RLIMIT_FSIZE with setrlimit to 0xffffffff and then fallocating 1 or more bytes at the offset of 0xffffffff should make the fallocate fail with EFBIG and generate a SIGXFSZ signal. On 64 bit platforms this works, on 32 bit platforms such as i386 Ubuntu bionic with 4.15 kernels it fails to generate EFBIG errors and SIGXFSZ. Attached is a test program to illustrate the problem. It sets the file size limit and allocates 1024 bytes at the boundary file size limit for 3 offsets: On 64 bit systems we get the expected results: got signal SIGXFSZ offset: 65536 (0x10000), fallocate returned: -1 got signal SIGXFSZ offset: 4294966271 (0xfffffbff), fallocate returned: -1 got signal SIGXFSZ offset: 4294967295 (0xffffffff), fallocate returned: -1 On 32 bit systems the code fails on the 0xffffffff offset: got signal SIGXFSZ offset: 65536 (0x10000), fallocate returned: -1 got signal SIGXFSZ offset: 4294966271 (0xfffffbff), fallocate returned: -1 offset: 4294967295 (0xffffffff), fallocate returned: 0 Attached is the reproducer. I found this while developing a file limit boundary test case in stress-ng and discovered it breaks on all 32 bit kernels (armhf, i386, etc), even with recent 5.15 kernels. This could be seen as a security issue; the sysadmin can set the file size limit and yet a 32 bit system can use a corner case like this to fallocate a much larger file by using the 0xffffffff offset and a huge fallocate size. To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1994079/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
