> This should be fixed, but > it's not as big an issue as the deadlock. Filesystems usually don't need > to worry about protecting a crafted image from acting weird and causing > damage to itself. I just thought that deadlocking a single thread is not much worse than further damaging already damaged FS and is not very dangerous (since it's not a NULL dereference or something like this). If it is or only malicious image can probably be damaged this way then I have no objections or further requests, so please excuse me for unclear wordings. Thanks, Anatoly вт, 10 июл. 2018 г. в 21:38, Ernesto A. Fernández <ernesto.mnd.fernandez@xxxxxxxxx>: > > On Tue, Jul 10, 2018 at 08:28:37PM +0300, Anatoly Trosinenko wrote: > > Thank you, > > > > When applied this single patch on v4.18-rc4 and performed "echo > > > /mnt/xyz" on hfsplus_16mb_hang image, I get about 14 pairs of lines > > > > hfsplus: unable to mark blocks free: error -5 > > hfsplus: can't free extent > > > > Then `echo` exits with "No space left on device" error. > > Truncation does not return error codes in hfsplus, hence this weird "No > space left" that comes from somewhere else. This should be fixed, but > it's not as big an issue as the deadlock. Filesystems usually don't need > to worry about protecting a crafted image from acting weird and causing > damage to itself. > > >Then it > > permits to perform `rm /mnt/xyz` and on `echo > /mnt/1` it responds > > with no space left on device (but file *is* created and is cattable). > > I don't know what is safer, but now it doesn't deadlock. :) Maybe it > > is even worth to remount FS r/o, I don't know. (Please excuse me for > > speculations) > > It's not strange that the /mnt/1 file could be created but not written > to, since the first operation doesn't usually require allocating blocks. > > > > > Thanks, > > Anatoly > > OK, I'll take a look at the truncation error codes as soon as I'm done > with the other deadlocks I found. It could take a while. > > Thanks for the testing. > Ernest > > > пн, 9 июл. 2018 г. в 23:35, Ernesto A. Fernández > > <ernesto.mnd.fernandez@xxxxxxxxx>: > > > > > > On Tue, Jun 12, 2018 at 09:43:26PM +0300, Anatoly Trosinenko wrote: > > > > And when I mount hfsplus_16mb_hang and perform `echo > /mnt/xyz`, it hangs. > > > > > > I just sent you a patch for this final report. Let me know if it works > > > for you.
