XPost: linux.debian.bugs.dist   
   From: carnil@debian.org   
      
   Control: forwarded -1 https://lore.kernel.org/lkml/9401208f-2db1   
   4397-a615-a03fd7520e53@amd.com/   
      
   On Wed, Nov 19, 2025 at 09:34:11PM +0100, Salvatore Bonaccorso wrote:   
   > Hi,   
   >   
   > On Wed, Nov 19, 2025 at 07:04:57PM +0100, Salvatore Bonaccorso wrote:   
   > > Hi,   
   > >   
   > > On Wed, Nov 19, 2025 at 03:03:51PM +0000, Luca Boccassi wrote:   
   > > > Source: linux   
   > > > Version: 6.18~rc6-1~exp1   
   > > > Severity: serious   
   > > > Justification: breaks other package's autopkgtest   
   > > >   
   > > > With kernel 6.18 from experimental mksquashfs segfaults roughly 1 in 4   
   > > > invocations. This does not happen with the kernel in unstable/testing,   
   > > > so it looks like a kernel regression.   
   > > >   
   > > > Filing at serious as it breaks systemd's autopkgtest:   
   > > > https://ci.debian.net/packages/s/systemd/unstable/amd64/66358275/#S67   
   > > >   
   > > > Trivial to reproduce:   
   > > >   
   > > > mkdir -p bar   
   > > > while mksquashfs bar bar.raw -noappend &>/dev/null; do true; done   
   > > >   
   > > > Decoded backtrace is strange, it looks like a pointer is corrupted.   
   > > > Different invocations result in slightly different crashes, although   
   > > > all seem to be in the xattr code handling, so that looks like a strong   
   > > > hint as to where things might have regressed.   
   > > >   
   > > > https://sources.debian.org/src/squashfs-tools/1%3A4.7.4-1/   
   quashfs-tools/xattr.c#L631   
   > > >   
   > > > #0  0x000055e3c9fddcd9 in read_xattrs (d=d@entry=0x55e3d1388be0,   
   > > > type=type@entry=1) at ./squashfs-tools/xattr.c:631   
   > > >         entry = 0x40e33   
   > > >         dir_ent =    
   > > >         inode =    
   > > >         filename = 0x7ffeb945bdbb "bar"   
   > > >         xattr_list = 0x0   
   > > >         head = 0x0   
   > > >         count = 0   
   > > >         i =    
   > > >         j =    
   > > >         l1 =  > > address 0x40e4b)>   
   > > >         l2 =    
   > > >         l3 =    
   > > >         action_add_list = 0x0   
   > > >         __func__ = "read_xattrs"   
   > > > #1  0x000055e3c9fb571f in create_inode   
   > > > (dir_info=dir_info@entry=0x55e3d1388b70, dir_ent=0x55e3d1388be0,   
   > > >     type=type@entry=1, byte_size=byte_size@entry=3,   
   > > > start_block=start_block@entry=0, offset=offset@entry=0,   
   > > >     block_list=0x0, fragment=0x0, dir_in=0x7ffeb9459840, sparse=0) at   
   > > > ./squashfs-tools/mksquashfs.c:1112   
   > > >         buf = 0x55e3d1388c30   
   > > >         inode_header = {base = {inode_type = 0, mode = 0, uid = 0,   
   > > > guid = 0, mtime = 3599334970,   
   > > >             inode_number = 32632}, dev = {inode_type = 0, mode = 0,   
   > > > uid = 0, guid = 0, mtime = 3599334970,   
   > > >             inode_number = 32632, nlink = 0, rdev = 0}, ldev =   
   > > > {inode_type = 0, mode = 0, uid = 0, guid = 0,   
   > > >             mtime = 3599334970, inode_number = 32632, nlink = 0, rdev   
   > > > = 0, xattr = 24080}, symlink = {   
   > > >             inode_type = 0, mode = 0, uid = 0, guid = 0, mtime =   
   > > > 3599334970, inode_number = 32632, nlink = 0,   
   > > >             symlink_size = 0, symlink = 0x7ffeb9459748 "\020^"}, reg =   
   > > > {inode_type = 0, mode = 0, uid = 0, guid = 0,   
   > > >             mtime = 3599334970, inode_number = 32632, start_block = 0,   
   > > > fragment = 0, offset = 24080, file_size = 0,   
   > > >             block_list = 0x7ffeb9459750}, lreg = {inode_type = 0, mode   
   > > > = 0, uid = 0, guid = 0, mtime = 3599334970,   
   > > >             inode_number = 32632, start_block = 0, file_size = 24080,   
   > > > sparse = 0, nlink = 0, fragment = 0,   
   > > >             offset = 0, xattr = 0, block_list = 0x7ffeb9459768}, dir =   
   > > > {inode_type = 0, mode = 0, uid = 0, guid = 0,   
   > > >             mtime = 3599334970, inode_number = 32632, start_block = 0,   
   > > > nlink = 0, file_size = 24080, offset = 0,   
   > > >             parent_inode = 0}, ldir = {inode_type = 0, mode = 0, uid =   
   > > > 0, guid = 0, mtime = 3599334970,   
   > > >             inode_number = 32632, nlink = 0, file_size = 0,   
   > > > start_block = 24080, parent_inode = 0, i_count = 0,   
   > > >             offset = 0, xattr = 0, index = 0x7ffeb9459758}, ipc =   
   > > > {inode_type = 0, mode = 0, uid = 0, guid = 0,   
   > > >             mtime = 3599334970, inode_number = 32632, nlink = 0}, lipc   
   > > > = {inode_type = 0, mode = 0, uid = 0,   
   > > >             guid = 0, mtime = 3599334970, inode_number = 32632, nlink   
   > > > = 0, xattr = 0}}   
   > > >         base = 0x7ffeb9459730   
   > > >         inode =    
   > > >         filename = 0x7ffeb945bdbb "bar"   
   > > >         nlink = 1   
   > > >         xattr =    
   > > >         uid =    
   > > >         gid =    
   > > >         mode =    
   > > > #2  0x000055e3c9fb68a0 in write_dir (dir_info=,   
   > > > dir=0x7ffeb9459840)   
   > > >     at ./squashfs-tools/mksquashfs.c:1522   
   > > >         dir_size =    
   > > >         data_space =    
   > > >         directory_block =    
   > > >         directory_offset =    
   > > >         i_count = 0   
   > > >         index = 16384   
   > > >         c_byte =    
   > > >         cache =    
   > > >         __func__ = "write_dir"   
   > > > #3  dir_scan8 (inode=, dir_info=) at   
   > > > ./squashfs-tools/mksquashfs.c:4647   
   > > >         squashfs_type =    
   > > >         dir =    
   > > >         dir_ent =    
   > > >         file =    
   > > > #4  0x000055e3c9fbaa85 in do_directory_scans   
   > > > (dir_ent=dir_ent@entry=0x55e3d1388be0, progress=progress@entry=1)   
   > > >     at ./squashfs-tools/mksquashfs.c:3620   
   > > >         inode = 208   
   > > >         pseudo =    
      
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