Fix linux virtual root device parsing #188
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frozencemetery
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When some Samsung NVMe devices have mutlipath mode enabled, that switches which kind of NVMe device shows up in sysfs, and we get a path link that's like "../../devices/virtual/nvme-subsystem/nvme-subsys0/nvme0n1". The first part of that, "../../devices/virtual/nvme-subsystem/", is supposed to be consumed by the parser in linux-virtual-root.c. Unfortunately, that parse loop incorrectly expects that sscanf will return nonzero when it parses the format string "%n../../devices/virtual/%n", but libc does not consider %n to be a conversion, and does not count it. In the log, we see it find the string and set pos, but rc is 0, and "current" is not advanced: linux-virtual-root.c:47 parse_virtual_root(): searching for ../../devices/virtual linux-virtual-root.c:50 parse_virtual_root(): current:'../../devices/virtual/nvme-subsystem/nvme-subsys0/nvme0n1' rc:0 pos0:0 pos1:22 linux-virtual-root.c:51 parse_virtual_root(): ^^^^^^^^^^^^^^^^^^^^^^ linux-virtual-root.c:47 parse_virtual_root(): searching for nvme-subsystem/ linux-virtual-root.c:50 parse_virtual_root(): current:'../../devices/virtual/nvme-subsystem/nvme-subsys0/nvme0n1' rc:0 pos0:0 pos1:-1 This patch makes it expect rc == 0, in the same way parse_acpi_root() in linux-acpi-root.c does. Signed-off-by: Peter Jones <pjones@redhat.com>
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I have received confirmation from one affected user that this resolves the issue. No reply from the others yet. |
frozencemetery
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When some Samsung NVMe devices have mutlipath mode enabled, that
switches which kind of NVMe device shows up in sysfs, and we get a
path link that's like
"../../devices/virtual/nvme-subsystem/nvme-subsys0/nvme0n1". The first
part of that, "../../devices/virtual/nvme-subsystem/", is supposed to be
consumed by the parser in linux-virtual-root.c. Unfortunately, that
parse loop incorrectly expects that sscanf will return nonzero when it
parses the format string "%n../../devices/virtual/%n", but libc does not
consider %n to be a conversion, and does not count it. In the log, we
see it find the string and set pos, but rc is 0, and "current" is not
advanced:
linux-virtual-root.c:47 parse_virtual_root(): searching for ../../devices/virtual
linux-virtual-root.c:50 parse_virtual_root(): current:'../../devices/virtual/nvme-subsystem/nvme-subsys0/nvme0n1' rc:0 pos0:0 pos1:22
linux-virtual-root.c:51 parse_virtual_root(): ^^^^^^^^^^^^^^^^^^^^^^
linux-virtual-root.c:47 parse_virtual_root(): searching for nvme-subsystem/
linux-virtual-root.c:50 parse_virtual_root(): current:'../../devices/virtual/nvme-subsystem/nvme-subsys0/nvme0n1' rc:0 pos0:0 pos1:-1
This patch makes it expect rc == 0, in the same way parse_acpi_root() in
linux-acpi-root.c does.
Signed-off-by: Peter Jones pjones@redhat.com