Description
In the Linux kernel, the following vulnerability has been resolved: pipe: preserve existing fasync readers on writer setup failure F_SETFL and FIOASYNC decide whether to invoke ->fasync() before pipe_fasync() takes pipe->mutex. Two enables of one O_RDWR FIFO can therefore both enter the callback. fasync_helper() allocates before checking for an existing entry. If the first enable installs both entries, a second enable can update the reader entry and then fail the allocation for the writer entry. The error path removes the pre-existing reader entry, clearing FASYNC while the writer entry remains registered. __fput() then skips ->fasync(), so a later pipe notification can dereference the freed file or its f_owner. An unprivileged memory-pressure reproducer triggers a KASAN slab-use-after-free in send_sigio() through this path. Keep the reader helper's result and undo the registration only if this call added it. The pipe mutex serializes changes to both lists, so a failed new registration still removes its reader, while a failed duplicate preserves the existing registrations and FASYNC. Successful duplicate enables continue to update fa_fd as before.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
76398425bb06b07cc3a3b1ce169c67dc9d6874ed to < 4c42ce499ce4b1c787e61082e3b13df4f30c4eaaaffected76398425bb06b07cc3a3b1ce169c67dc9d6874ed to < 2259809e5b7043c4ba20af7b14ba3e471cf55521affected76398425bb06b07cc3a3b1ce169c67dc9d6874ed to < 40bb03d3ea6f6a915218508819ecc4d7a7fa260daffected
Linux Linux
Default version status: affected
2.6.30affected0 to < 2.6.30unaffected6.18.59 to ≤ 6.18.*unaffected7.2.13 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected