Messages in this thread Patch in this message |  | | From | Jiri Slaby <> | Subject | [PATCH] fs: pipe, fix undefined behaviour | Date | Fri, 14 Oct 2016 11:23:42 +0200 |
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echo | ./program where ./program contains fcntl(0, F_SETPIPE_SZ, 0) this is triggered: UBSAN: Undefined behaviour in ../include/linux/log2.h:63:13 shift exponent 64 is too large for 64-bit type 'long unsigned int' CPU: 3 PID: 4978 Comm: syz-executor Not tainted 4.8.1-0-syzkaller #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.1-0-gb3ef39f-prebuilt.qemu-project.org 04/01/2014 ... Call Trace: ... [<ffffffffa18ced53>] ? pipe_fcntl+0xa3/0x7a0 [<ffffffffa18f1940>] ? SyS_fcntl+0x930/0xf30 [<ffffffffa2d1fb00>] ? entry_SYSCALL_64_fastpath+0x23/0xc1
Documentaion of roundup_pow_of_two explicitly mentions that passing size 0 is undefined. So return 0 from round_pipe_size prematurely to fix this.
Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org --- fs/pipe.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/pipe.c b/fs/pipe.c index 8e0d9f26dfad..23c0c06ffc33 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -1024,6 +1024,9 @@ static inline unsigned int round_pipe_size(unsigned int size) { unsigned long nr_pages; + if (!size) + return 0; + nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; return roundup_pow_of_two(nr_pages) << PAGE_SHIFT; } -- 2.10.1
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