From 913e027ca17ee06fa9436a21e54464795b0fa0e8 Mon Sep 17 00:00:00 2001 From: Dmitry Monakhov Date: Tue, 10 Feb 2015 14:09:29 -0800 Subject: [PATCH] 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 Cc: Theodore Ts'o Cc: Al Viro Cc: Michael Kerrisk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/filesystems/fiemap.txt | 3 ++- fs/ioctl.c | 5 +++++ 2 files changed, 7 insertions(+), 1 deletion(-) 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 */ -- 2.11.0