mainlining shenanigans
2e43f95dd8
If first_sg and last_sg wraps around in the scatterlist ring, then we
need to account for that in the shift as well. E.g. crafting such msgs
where this is the case leads to a hang as shift becomes negative. E.g.
consider the following scenario:
first_sg := 14 |=> shift := -12 msg->sg_start := 10
last_sg := 3 | msg->sg_end := 5
round 1: i := 15, move_from := 3, sg[15] := sg[ 3]
round 2: i := 0, move_from := -12, sg[ 0] := sg[-12]
round 3: i := 1, move_from := -11, sg[ 1] := sg[-11]
round 4: i := 2, move_from := -10, sg[ 2] := sg[-10]
[...]
round 13: i := 11, move_from := -1, sg[ 2] := sg[ -1]
round 14: i := 12, move_from := 0, sg[ 2] := sg[ 0]
round 15: i := 13, move_from := 1, sg[ 2] := sg[ 1]
round 16: i := 14, move_from := 2, sg[ 2] := sg[ 2]
round 17: i := 15, move_from := 3, sg[ 2] := sg[ 3]
[...]
This means we will loop forever and never hit the msg->sg_end condition
to break out of the loop. When we see that the ring wraps around, then
the shift should be MAX_SKB_FRAGS - first_sg + last_sg - 1. Meaning,
the remainder slots from the tail of the ring and the head until last_sg
combined.
Fixes:
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arch | ||
block | ||
certs | ||
crypto | ||
Documentation | ||
drivers | ||
firmware | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
LICENSES | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | ||
.cocciconfig | ||
.get_maintainer.ignore | ||
.gitattributes | ||
.gitignore | ||
.mailmap | ||
COPYING | ||
CREDITS | ||
Kbuild | ||
Kconfig | ||
MAINTAINERS | ||
Makefile | ||
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. See Documentation/00-INDEX for a list of what is contained in each file. 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.