exec: Fix mem leak in kernel_read_file

YueHaibing · Al Viro · commit f612acfae86a · 2019-02-18T21:26:24.000-05:00
syzkaller report this: BUG: memory leak unreferenced object 0xffffc9000488d000 (size 9195520): comm "syz-executor.0", pid 2752, jiffies 4294787496 (age 18.757s) hex dump (first 32 bytes): ff ff ff ff ff ff ff ff a8 00 00 00 01 00 00 00 ................ 02 00 00 00 00 00 00 00 80 a1 7a c1 ff ff ff ff ..........z..... backtrace: [<000000000863775c>] __vmalloc_node mm/vmalloc.c:1795 [inline] [<000000000863775c>] __vmalloc_node_flags mm/vmalloc.c:1809 [inline] [<000000000863775c>] vmalloc+0x8c/0xb0 mm/vmalloc.c:1831 [<000000003f668111>] kernel_read_file+0x58f/0x7d0 fs/exec.c:924 [<000000002385813f>] kernel_read_file_from_fd+0x49/0x80 fs/exec.c:993 [<0000000011953ff1>] __do_sys_finit_module+0x13b/0x2a0 kernel/module.c:3895 [<000000006f58491f>] do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290 [<00000000ee78baf4>] entry_SYSCALL_64_after_hwframe+0x49/0xbe [<00000000241f889b>] 0xffffffffffffffff It should goto 'out_free' lable to free allocated buf while kernel_read fails. Fixes: 39d637a ("vfs: forbid write access when reading a file into memory") Signed-off-by: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/exec.c b/fs/exec.c
@@ -932,7 +932,7 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
 		bytes = kernel_read(file, *buf + pos, i_size - pos, &pos);
 		if (bytes < 0) {
 			ret = bytes;
-			goto out;
+			goto out_free;
 		}
 
 		if (bytes == 0)

Original file line number	Diff line number	Diff line change
`@@ -932,7 +932,7 @@ int kernel_read_file(struct file file, void buf, loff_t size,`
`932`	`932`	`bytes = kernel_read(file, *buf + pos, i_size - pos, &pos);`
`933`	`933`	`if (bytes < 0) {`
`934`	`934`	`ret = bytes;`
`935`		`- goto out;`
	`935`	`+ goto out_free;`
`936`	`936`	`}`
`937`	`937`
`938`	`938`	`if (bytes == 0)`