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authorDmitry Monakhov <dmonakhov@openvz.org>2015-02-10 14:09:29 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-10 14:30:30 -0800
commit913e027ca17ee06fa9436a21e54464795b0fa0e8 (patch)
treed583200d611573204224ac54bb7f7f1a633950ef
parent99b8874e79619498ade354357f64299768642af6 (diff)
fsioctl.c: make generic_block_fiemap() signal-tolerant
__generic_block_fiemap may spin very long time for large sparse files. Without this patch an unprivileged user may abuse system resources simply by spawning a vast number of unkilable busyloops (works on ext2/ext3): truncate --size 1T test for ((i=0;i<1024;i++)) do filefrag test > /dev/null & done Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--Documentation/filesystems/fiemap.txt3
-rw-r--r--fs/ioctl.c5
2 files changed, 7 insertions, 1 deletions
diff --git a/Documentation/filesystems/fiemap.txt b/Documentation/filesystems/fiemap.txt
index 1b805a0efbb0..f6d9c99103a4 100644
--- a/Documentation/filesystems/fiemap.txt
+++ b/Documentation/filesystems/fiemap.txt
@@ -196,7 +196,8 @@ struct fiemap_extent_info {
};
It is intended that the file system should not need to access any of this
-structure directly.
+structure directly. Filesystem handlers should be tolerant to signals and return
+EINTR once fatal signal received.
Flag checking should be done at the beginning of the ->fiemap callback via the
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 214c3c11fbc2..5d01d2638ca5 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -379,6 +379,11 @@ int __generic_block_fiemap(struct inode *inode,
past_eof = true;
}
cond_resched();
+ if (fatal_signal_pending(current)) {
+ ret = -EINTR;
+ break;
+ }
+
} while (1);
/* If ret is 1 then we just hit the end of the extent array */