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Yonghong Song b36e62eb85 bpf: Use strncpy_from_unsafe_strict() in bpf_seq_printf() helper
In bpf_seq_printf() helper, when user specified a "%s" in the
format string, strncpy_from_unsafe() is used to read the actual string
to a buffer. The string could be a format string or a string in
the kernel data structure. It is really unlikely that the string
will reside in the user memory.

This is different from Commit b2a5212fb6 ("bpf: Restrict bpf_trace_printk()'s %s
usage and add %pks, %pus specifier") which still used
strncpy_from_unsafe() for "%s" to preserve the old behavior.

If in the future, bpf_seq_printf() indeed needs to read user
memory, we can implement "%pus" format string.

Based on discussion in [1], if the intent is to read kernel memory,
strncpy_from_unsafe_strict() should be used. So this patch
changed to use strncpy_from_unsafe_strict().

[1]: https://lore.kernel.org/bpf/20200521152301.2587579-1-hch@lst.de/T/

Fixes: 492e639f0c ("bpf: Add bpf_seq_printf and bpf_seq_write helpers")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/bpf/20200529004810.3352219-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-06-01 14:48:31 -07:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-05-31 17:48:46 -07:00
block Revert "block: end bio with BLK_STS_AGAIN in case of non-mq devs and REQ_NOWAIT" 2020-05-28 13:20:39 -06:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto gcc-10: avoid shadowing standard library 'free()' in crypto 2020-05-09 15:58:04 -07:00
Documentation docs/bpf: Add BPF ring buffer design notes 2020-06-01 14:38:22 -07:00
drivers net: dsa: sja1105: suppress -Wmissing-prototypes in sja1105_vl.c 2020-06-01 12:13:47 -07:00
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-05-31 17:48:46 -07:00
include bpf: Add rx_queue_mapping to bpf_sock 2020-06-01 14:38:23 -07:00
init A single fix for early boot crashes of kernels built with gcc10 and 2020-05-17 11:08:29 -07:00
ipc Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-05-15 13:48:59 -07:00
kernel bpf: Use strncpy_from_unsafe_strict() in bpf_seq_printf() helper 2020-06-01 14:48:31 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-05-24 13:47:27 -07:00
LICENSES
mm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-05-31 17:48:46 -07:00
net bpf: Add rx_queue_mapping to bpf_sock 2020-06-01 14:38:23 -07:00
samples samples, bpf: Refactor kprobe, tail call kern progs map definition 2020-05-19 17:13:03 +02:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-05-31 17:48:46 -07:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-05-31 17:48:46 -07:00
sound sound fixes for 5.7 (rc8 or final) 2020-05-29 13:31:01 -07:00
tools bpf: Add BPF ringbuf and perf buffer benchmarks 2020-06-01 14:38:22 -07:00
usr kbuild: fix comment about missing include guard detection 2020-04-11 12:09:48 +09:00
virt KVM: Introduce kvm_make_all_cpus_request_except() 2020-05-08 07:44:32 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2020-04-18 13:49:33 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
.mailmap i2c: use my kernel.org address from now on 2020-05-05 16:29:09 +02:00
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MAINTAINERS MAINTAINERS: Adjust entry in XDP SOCKETS to actual file name 2020-06-01 14:38:19 -07:00
Makefile Linux 5.7-rc7 2020-05-24 15:32:54 -07:00
README

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.