nbd: Don't fail handshake on NBD_OPT_LIST descriptions

The NBD Protocol states that NBD_REP_SERVER may set
'length > sizeof(namelen) + namelen'; in which case the rest
of the packet is a UTF-8 description of the export.  While we
don't know of any NBD servers that send this description yet,
we had better consume the data so we don't choke when we start
to talk to such a server.

Also, a (buggy/malicious) server that replies with length <
sizeof(namelen) would cause us to block waiting for bytes that
the server is not sending, and one that replies with super-huge
lengths could cause us to temporarily allocate up to 4G memory.
Sanity check things before blindly reading incorrectly.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-id: 1460077777-31004-1-git-send-email-eblake@redhat.com
Reviewed-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Max Reitz <mreitz@redhat.com>
1 file changed
tree: d534ed7efe5cad2237678e5976844777ae70b5c1
  1. audio/
  2. backends/
  3. block/
  4. bsd-user/
  5. contrib/
  6. crypto/
  7. default-configs/
  8. disas/
  9. docs/
  10. fpu/
  11. fsdev/
  12. gdb-xml/
  13. hw/
  14. include/
  15. io/
  16. libdecnumber/
  17. linux-headers/
  18. linux-user/
  19. migration/
  20. nbd/
  21. net/
  22. pc-bios/
  23. po/
  24. qapi/
  25. qga/
  26. qobject/
  27. qom/
  28. replay/
  29. roms/
  30. scripts/
  31. slirp/
  32. stubs/
  33. target-alpha/
  34. target-arm/
  35. target-cris/
  36. target-i386/
  37. target-lm32/
  38. target-m68k/
  39. target-microblaze/
  40. target-mips/
  41. target-moxie/
  42. target-openrisc/
  43. target-ppc/
  44. target-s390x/
  45. target-sh4/
  46. target-sparc/
  47. target-tilegx/
  48. target-tricore/
  49. target-unicore32/
  50. target-xtensa/
  51. tcg/
  52. tests/
  53. trace/
  54. ui/
  55. util/
  56. .dir-locals.el
  57. .exrc
  58. .gitignore
  59. .gitmodules
  60. .mailmap
  61. .travis.yml
  62. accel.c
  63. aio-posix.c
  64. aio-win32.c
  65. arch_init.c
  66. async.c
  67. balloon.c
  68. block.c
  69. blockdev-nbd.c
  70. blockdev.c
  71. blockjob.c
  72. bootdevice.c
  73. bt-host.c
  74. bt-vhci.c
  75. Changelog
  76. CODING_STYLE
  77. configure
  78. COPYING
  79. COPYING.LIB
  80. cpu-exec-common.c
  81. cpu-exec.c
  82. cpus.c
  83. cputlb.c
  84. device-hotplug.c
  85. device_tree.c
  86. disas.c
  87. dma-helpers.c
  88. dump.c
  89. exec.c
  90. gdbstub.c
  91. HACKING
  92. hmp-commands-info.hx
  93. hmp-commands.hx
  94. hmp.c
  95. hmp.h
  96. iohandler.c
  97. ioport.c
  98. iothread.c
  99. kvm-all.c
  100. kvm-stub.c
  101. LICENSE
  102. main-loop.c
  103. MAINTAINERS
  104. Makefile
  105. Makefile.objs
  106. Makefile.target
  107. memory.c
  108. memory_mapping.c
  109. module-common.c
  110. monitor.c
  111. numa.c
  112. os-posix.c
  113. os-win32.c
  114. page_cache.c
  115. qapi-schema.json
  116. qdev-monitor.c
  117. qdict-test-data.txt
  118. qemu-bridge-helper.c
  119. qemu-char.c
  120. qemu-doc.texi
  121. qemu-ga.texi
  122. qemu-img-cmds.hx
  123. qemu-img.c
  124. qemu-img.texi
  125. qemu-io-cmds.c
  126. qemu-io.c
  127. qemu-nbd.c
  128. qemu-nbd.texi
  129. qemu-options-wrapper.h
  130. qemu-options.h
  131. qemu-options.hx
  132. qemu-seccomp.c
  133. qemu-tech.texi
  134. qemu-timer.c
  135. qemu.nsi
  136. qemu.sasl
  137. qjson.c
  138. qmp-commands.hx
  139. qmp.c
  140. qtest.c
  141. README
  142. rules.mak
  143. softmmu_template.h
  144. spice-qemu-char.c
  145. tcg-runtime.c
  146. tci.c
  147. thread-pool.c
  148. thunk.c
  149. tpm.c
  150. trace-events
  151. translate-all.c
  152. translate-all.h
  153. translate-common.c
  154. user-exec.c
  155. VERSION
  156. version.rc
  157. vl.c
  158. xen-common-stub.c
  159. xen-common.c
  160. xen-hvm-stub.c
  161. xen-hvm.c
  162. xen-mapcache.c