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42378a9ca5
If an error (NULL) is returned by krealloc(), callers of realloc_array()
were setting their allocation pointers to NULL, but on error krealloc()
does not touch the original allocation. This would result in a memory
resource leak. Instead, free the old allocation on the error handling
path.
The memory leak information is as follows as also reported by Zhengchao:
unreferenced object 0xffff888019801800 (size 256):
comm "bpf_repo", pid 6490, jiffies 4294959200 (age 17.170s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<00000000b211474b>] __kmalloc_node_track_caller+0x45/0xc0
[<0000000086712a0b>] krealloc+0x83/0xd0
[<00000000139aab02>] realloc_array+0x82/0xe2
[<00000000b1ca41d1>] grow_stack_state+0xfb/0x186
[<00000000cd6f36d2>] check_mem_access.cold+0x141/0x1341
[<0000000081780455>] do_check_common+0x5358/0xb350
[<0000000015f6b091>] bpf_check.cold+0xc3/0x29d
[<000000002973c690>] bpf_prog_load+0x13db/0x2240
[<00000000028d1644>] __sys_bpf+0x1605/0x4ce0
[<00000000053f29bd>] __x64_sys_bpf+0x75/0xb0
[<0000000056fedaf5>] do_syscall_64+0x35/0x80
[<000000002bd58261>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
Fixes: c69431aab6 ("bpf: verifier: Improve function state reallocation")
Reported-by: Zhengchao Shao <shaozhengchao@huawei.com>
Reported-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Bill Wendling <morbo@google.com>
Cc: Lorenz Bauer <oss@lmb.io>
Link: https://lore.kernel.org/bpf/20221029025433.2533810-1-keescook@chromium.org
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.