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| H A D | seq_file.c | diff 05e16745 Fri Oct 25 04:15:06 MDT 2013 Gu Zheng <guz.fnst@cn.fujitsu.com> seq_file: always update file->f_pos in seq_lseek() This issue was first pointed out by Jiaxing Wang several months ago, but no further comments: https://lkml.org/lkml/2013/6/29/41 As we know pread() does not change f_pos, so after pread(), file->f_pos and m->read_pos become different. And seq_lseek() does not update file->f_pos if offset equals to m->read_pos, so after pread() and seq_lseek()(lseek to m->read_pos), then a subsequent read may read from a wrong position, the following program produces the problem: char str1[32] = { 0 }; char str2[32] = { 0 }; int poffset = 10; int count = 20; /*open any seq file*/ int fd = open("/proc/modules", O_RDONLY); pread(fd, str1, count, poffset); printf("pread:%s\n", str1); /*seek to where m->read_pos is*/ lseek(fd, poffset+count, SEEK_SET); /*supposed to read from poffset+count, but this read from position 0*/ read(fd, str2, count); printf("read:%s\n", str2); out put: pread: ck_netbios_ns 12665 read: nf_conntrack_netbios /proc/modules: nf_conntrack_netbios_ns 12665 0 - Live 0xffffffffa038b000 nf_conntrack_broadcast 12589 1 nf_conntrack_netbios_ns, Live 0xffffffffa0386000 So we always update file->f_pos to offset in seq_lseek() to fix this issue. Signed-off-by: Jiaxing Wang <hello.wjx@gmail.com> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> diff 05e16745 Fri Oct 25 04:15:06 MDT 2013 Gu Zheng <guz.fnst@cn.fujitsu.com> seq_file: always update file->f_pos in seq_lseek() This issue was first pointed out by Jiaxing Wang several months ago, but no further comments: https://lkml.org/lkml/2013/6/29/41 As we know pread() does not change f_pos, so after pread(), file->f_pos and m->read_pos become different. And seq_lseek() does not update file->f_pos if offset equals to m->read_pos, so after pread() and seq_lseek()(lseek to m->read_pos), then a subsequent read may read from a wrong position, the following program produces the problem: char str1[32] = { 0 }; char str2[32] = { 0 }; int poffset = 10; int count = 20; /*open any seq file*/ int fd = open("/proc/modules", O_RDONLY); pread(fd, str1, count, poffset); printf("pread:%s\n", str1); /*seek to where m->read_pos is*/ lseek(fd, poffset+count, SEEK_SET); /*supposed to read from poffset+count, but this read from position 0*/ read(fd, str2, count); printf("read:%s\n", str2); out put: pread: ck_netbios_ns 12665 read: nf_conntrack_netbios /proc/modules: nf_conntrack_netbios_ns 12665 0 - Live 0xffffffffa038b000 nf_conntrack_broadcast 12589 1 nf_conntrack_netbios_ns, Live 0xffffffffa0386000 So we always update file->f_pos to offset in seq_lseek() to fix this issue. Signed-off-by: Jiaxing Wang <hello.wjx@gmail.com> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> diff 6131ffaa Wed Feb 27 14:59:05 MST 2013 Al Viro <viro@zeniv.linux.org.uk> more file_inode() open-coded instances Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> diff 02125a82 Mon Dec 05 06:43:34 MST 2011 Al Viro <viro@zeniv.linux.org.uk> fix apparmor dereferencing potentially freed dentry, sanitize __d_path() API __d_path() API is asking for trouble and in case of apparmor d_namespace_path() getting just that. The root cause is that when __d_path() misses the root it had been told to look for, it stores the location of the most remote ancestor in *root. Without grabbing references. Sure, at the moment of call it had been pinned down by what we have in *path. And if we raced with umount -l, we could have very well stopped at vfsmount/dentry that got freed as soon as prepend_path() dropped vfsmount_lock. It is safe to compare these pointers with pre-existing (and known to be still alive) vfsmount and dentry, as long as all we are asking is "is it the same address?". Dereferencing is not safe and apparmor ended up stepping into that. d_namespace_path() really wants to examine the place where we stopped, even if it's not connected to our namespace. As the result, it looked at ->d_sb->s_magic of a dentry that might've been already freed by that point. All other callers had been careful enough to avoid that, but it's really a bad interface - it invites that kind of trouble. The fix is fairly straightforward, even though it's bigger than I'd like: * prepend_path() root argument becomes const. * __d_path() is never called with NULL/NULL root. It was a kludge to start with. Instead, we have an explicit function - d_absolute_root(). Same as __d_path(), except that it doesn't get root passed and stops where it stops. apparmor and tomoyo are using it. * __d_path() returns NULL on path outside of root. The main caller is show_mountinfo() and that's precisely what we pass root for - to skip those outside chroot jail. Those who don't want that can (and do) use d_path(). * __d_path() root argument becomes const. Everyone agrees, I hope. * apparmor does *NOT* try to use __d_path() or any of its variants when it sees that path->mnt is an internal vfsmount. In that case it's definitely not mounted anywhere and dentry_path() is exactly what we want there. Handling of sysctl()-triggered weirdness is moved to that place. * if apparmor is asked to do pathname relative to chroot jail and __d_path() tells it we it's not in that jail, the sucker just calls d_absolute_path() instead. That's the other remaining caller of __d_path(), BTW. * seq_path_root() does _NOT_ return -ENAMETOOLONG (it's stupid anyway - the normal seq_file logics will take care of growing the buffer and redoing the call of ->show() just fine). However, if it gets path not reachable from root, it returns SEQ_SKIP. The only caller adjusted (i.e. stopped ignoring the return value as it used to do). Reviewed-by: John Johansen <john.johansen@canonical.com> ACKed-by: John Johansen <john.johansen@canonical.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@vger.kernel.org diff 7a62cc10 Fri Sep 18 14:05:59 MDT 2009 Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> seq_file: return a negative error code when seq_path_root() fails. seq_path_root() is returning a return value of successful __d_path() instead of returning a negative value when mangle_path() failed. This is not a bug so far because nobody is using return value of seq_path_root(). Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> diff 0b923606 Wed Jun 17 17:28:05 MDT 2009 Peter Oberparleiter <oberpar@linux.vnet.ibm.com> seq_file: add function to write binary data seq_write() can be used to construct seq_files containing arbitrary data. Required by the gcov-profiling interface to synthesize binary profiling data files. Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Huang Ying <ying.huang@intel.com> Cc: Li Wei <W.Li@Sun.COM> Cc: Michael Ellerman <michaele@au1.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com> Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: WANG Cong <xiyou.wangcong@gmail.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Jeff Dike <jdike@addtoit.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff af76aba0 Mon Mar 30 22:05:11 MDT 2009 Rusty Russell <rusty@rustcorp.com.au> cpumask: fix seq_bitmap_*() functions. 1) seq_bitmap_list() should take a const. 2) All the seq_bitmap should use cpumask_bits(). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> diff f01d1d54 Thu Feb 05 14:30:05 MST 2009 Alexey Dobriyan <adobriyan@gmail.com> seq_file: fix big-enough lseek() + read() lseek() further than length of the file will leave stale ->index (second-to-last during iteration). Next seq_read() will not notice that ->f_pos is big enough to return 0, but will print last item as if ->f_pos is pointing to it. Introduced in commit cb510b8172602a66467f3551b4be1911f5a7c8c2 aka "seq_file: more atomicity in traverse()". Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff f01d1d54 Thu Feb 05 14:30:05 MST 2009 Alexey Dobriyan <adobriyan@gmail.com> seq_file: fix big-enough lseek() + read() lseek() further than length of the file will leave stale ->index (second-to-last during iteration). Next seq_read() will not notice that ->f_pos is big enough to return 0, but will print last item as if ->f_pos is pointing to it. Introduced in commit cb510b8172602a66467f3551b4be1911f5a7c8c2 aka "seq_file: more atomicity in traverse()". Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 4cdfe84b Sun Aug 24 05:45:33 MDT 2008 Al Viro <viro@zeniv.linux.org.uk> [PATCH] deal with the first call of ->show() generating no output seq_read() has a subtle bug - we want the first loop there to go until at least one *non-empty* record had fit entirely into buffer. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
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