Cherry-pick #15771 to 7.6: Socket dataset: Workaround for bogus dereference in kernel 5.x #15792
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…ic#15771) This is a tentative workaround for the problems in Auditbeat's system/socket dataset when run under 5.x kernels. On older kernels, we could rely on dereferencing a NULL or invalid pointer returning zeroed memory. However, seems that in the tested 5.x kernels is not the case. Dereferencing a NULL pointer returns bogus memory, which causes some wrong codepaths to be taken in a couple of kprobes defined by the dataset. This so far seems only to affect udp_sendmsg and udpv6_sendmsg, which caused it to attribute traffic to bogus IP addresses. In turn this caused the test-connected-udp system tests to fail. (cherry picked from commit 0dab517)
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Cherry-pick of PR #15771 to 7.6 branch. Original message:
This is a tentative workaround for the problems in Auditbeat's system/socket dataset when run under 5.x kernels.
On older kernels, we could rely on dereferencing a NULL or invalid pointer returning zeroed memory. However, seems that in the tested 5.x kernels is not the case. Dereferencing a NULL pointer returns bogus memory, which causes some wrong codepaths to be taken in a couple of
kprobes defined by the dataset.
This so far seems only to affect udp_sendmsg and udpv6_sendmsg, which caused it to attribute traffic to bogus IP addresses. In turn this caused the test-connected-udp system tests to fail.
In parallel I'm trying to find the reason for this different behavior and ideally have the tracing subsystem behave like in previous versions, so this patch is not needed.