概要

In the Linux kernel, the following vulnerability has been resolved:net/iucv: fix use after free in iucv_sock_close()iucv_sever_path() is called from process context and from bh context.iucv-&gt;path is used as indicator whether somebody else is taking care ofsevering the path (or it is already removed / never existed).This needs to be done with atomic compare and swap, otherwise there is asmall window where iucv_sock_close() will try to work with a path that hasalready been severed and freed by iucv_callback_connrej() called byiucv_tasklet_fn().Example:[452744.123844] Call Trace:[452744.123845] ([<0000001e87f03880&gt;] 0x1e87f03880)[452744.123966] [<00000000d593001e&gt;] iucv_path_sever+0x96/0x138[452744.124330] [<000003ff801ddbca&gt;] iucv_sever_path+0xc2/0xd0 [af_iucv][452744.124336] [<000003ff801e01b6&gt;] iucv_sock_close+0xa6/0x310 [af_iucv][452744.124341] [<000003ff801e08cc&gt;] iucv_sock_release+0x3c/0xd0 [af_iucv][452744.124345] [<00000000d574794e&gt;] __sock_release+0x5e/0xe8[452744.124815] [<00000000d5747a0c&gt;] sock_close+0x34/0x48[452744.124820] [<00000000d5421642&gt;] __fput+0xba/0x268[452744.124826] [<00000000d51b382c&gt;] task_work_run+0xbc/0xf0[452744.124832] [<00000000d5145710&gt;] do_notify_resume+0x88/0x90[452744.124841] [<00000000d5978096&gt;] system_call+0xe2/0x2c8[452744.125319] Last Breaking-Event-Address:[452744.125321] [<00000000d5930018&gt;] iucv_path_sever+0x90/0x138[452744.125324][452744.125325] Kernel panic - not syncing: Fatal exception in interruptNote that bh_lock_sock() is not serializing the tasklet context againstprocess context, because the check for sock_owned_by_user() andcorresponding handling is missing.Ideas for a future clean-up patch:A) Correct usage of bh_lock_sock() in tasklet context, as described inRe-enqueue, if needed. This may require adding return values to thetasklet functions and thus changes to all users of iucv.B) Change iucv tasklet into worker and use only lock_sock() in af_iucv.

CVSS v3 指标

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